This was actually just a "general" sketch I had done more than a month ago. I have several of these. They're useful when the location isn't as important as the text or characters.

Astute readers will notice that the sketch I used for the "In The Works" image didn't actually show up in the final strip. There are a few reasons for that, but mainly, it's my strip, and I changed my mind about what I wanted to do with it. :) You'll live.

Once I have thought out the dialogue and layout of the strip, I needed to draw it. Actually, dialogue is a huge part of the layout, and probably mostly overlooked by amateur comic artists. I make a special effort (most times) to make sure that I A: have enough room for the dialogue (word bubbles), and B: the layout of the panels and placement of the characters are conducive to readability. I've messed up a few times, but I'm working on it.

This is "actual size" on paper, though on this page it's been shrunk down for viewing. Sometimes my format sketches are smaller than the final drawing size (which fills most of an 8.5"x11"). In those cases, I use my scanner as a photocopier to enlarge the sketch, in order to make a full-size ink.

Note that the scan is pretty light - I've actually darkened it a bit. I don't usually ink right over my pencils, but lately with R.D.T. strips, if I manage to do my pencils neatly (and not press too hard or erase all over the place) then I'll use the same sheet for inking.
Also note that I didn't do the books at all - the background I left as a "suggestion," though I DID straighten the shelves out. Incidentally, I use a T-square for straight lines (including the borders), which ensures that the line I draw will be perpendicular to the edges of the paper.

Ms. Harper in this case was traced via lightbox from the sketch, since she doesn't move. Why redraw something twice when you did it fine the first time? However, her relative position changed in the sketch, to better fit the panel's layout. The panel needs to fit Davis, Ms. Harper, as well as the partially-shown stack of books.
The other thing I keep in mind when doing the formatted sketch is the placement of the characters not only in the panel, but to each other. Davis's hand is pretty much touching Ms. Harper. That's probably a mistake on my part, I should have let his hand overlap her a little. It would have suggested depth, instead I got sort of a "cramped" look. Ah well, c'est la vie.

Note that I have left a lot of empty space for word balloons. This is when I also begin to think about color. More on that later.

In this instance, I've inked right over my pencils, and then erased the pencil. I can't do that with all of my strips, either because I've gone over the pencils so much as to marr the paper, or because the strips were sort of "all over the place." In those cases, it's easier to use a lightbox to re-draw the inked version on a new sheet of paper.

I did use a lightbox on this piece to duplicate the bookshelves (as well as Ms. Harper, earlier). After drawing them neatly (with my .01 pen and t-square) in the left-hand panel, I photocopied it with my scanner, and used a lightbox to trace the right-hand panel from it. This way, I get the same background without making a hundred mistakes. 

I use pens of different width to suggest foreground and depth. It's hard to tell in this small version, but the outline around Davis and Ms. Harper (and the stack of books) is slightly thicker than the lines I used for the books/bookshelves. This "pops" them out into the foreground. It's an old trick. Also notice the thickest line is around the panel borders. That way it acts more as a "frame."

I already knew that I wanted to experiment with a different coloring style with this strip. Up to this point, I had been inking with little depth, and relying on the coloring process to put things in the background or foreground, to render it more or less important to the eye. With this strip (and possibly future ones) I wanted to color it "flatly" - saving me time in the long run, hopefully, and making the panels look less "cluttered" with color. Line width is crucial to flat-color comics, because that is where you're going to get your depth.

Incidentally, for those who like comics and want to read more about the mechanics and methods in them, check out Scott McCloud's Understanding Comics. It's an excellent book and really illustrates a lot of the theory and planning that goes into a comic. There are quite a few "unnoticed" aspects of a comic that are essential to a successful strip. He also has a book called Reinventing Comics that is geared specifically toward webcomics. I haven't read it, but I have heard that it's also quite good.

I'm a big color buff. I'm usually more interested in the coloring techniques in an image than the actual drawing techniques. My own style is relatively simple, so it makes it easy to color each R.D.T. strip. A lot of webcomics out there either A: aren't colored, or B: are colored digitally. For that reason I decided to color R.D.T. with markers, though digital coloring would probably have been faster. (I still use digital coloring in some cases - there was one strip which I am planning on redoing, and there is the 4th of July image/strip. That project was too big to take on with just markers.)
In some cases, I do fill in the backgrounds digitally. If there is a large area of blank wall, I'll use PhotoShop's "Fill" tool rather than use up my $3-apiece markers. I'm still working on getting the "filled" portions to mesh well with the hand-coloring. In this case however, it's all marker.

Generally, when I do a background, I use "muted" colors. This way the brighter colors (like the colors I use for hair and clothes) will visually stand out, helping put them into the foreground. In this case however, I felt free to use dozens of colors for the books. Why? The books are small. The figures are large. Their clothes are larger areas of color than any of the books. The "mosaic" of colored books in the back actually makes them fairly uninteresting to the eye (without being a boring background), whereas the bright, large color on Davis and Ms. Harper immediately draw the eye. "Hey, we're big, look at us!" Additionally, the books are all linear and relatively uniform. Ms. Harper and Davis's organic shapes pull them out of the background, also. I would never have made a background that busy if they weren't all rectangular. Note that I used some of the same colors in both their clothes AND the books - this is a visual trick to help "mesh" the fore and backgrounds, so they don't look like they're just stuck onto a background.

Note the second-to-bottom row of books. They're all the same color (they're a Dangerous Thing, keep an eye out for them in the Danger Showcase.) They're encyclopedic in nature, so needed to match, color-wise. Rather than risk drawing attention to them, I colored them a "middle grey." You notice them (which is good, since they're a featured Dangerous Thing) but they don't detract from the foreground at all.

The last note about this process is the extent to which I colored. I KNEW there would be word bubbles above and to the right of Ms. Harper - but I colored those areas anyway. Some people don't bother coloring what they know will get covered up, but I don't do that. I don't like leaving things incomplete anyway, but I also never know when I might want a "bubble-free" version, or something. It just makes for nicer originals.

On a technical note, I add the word bubbles in Adobe's PhotoShop. It's easier than you think. First I use the type tool to write the words I want, in the font I want. For instance, most dialogue is done with A.C.M.E. Secret Agent 10pt (Blambot). Davis's whining is done in Wichita 16pt (Ray Larabie?). I move those text layers to where I want them to be.

Then I make a new layer that is between the background (the strip) and all the text layers. Using the oval-select tool, I draw the bubbles. You can move them to fit correctly around the text if you misjudged the origin point. By "correctly," I mean that the text should fit comfortably inside the bubble, with "breathing room" all around. Otherwise the words look cramped. Then, Edit-> Fill-> Foreground Color (which I set to white.) Do that for all the word bubbles, then use the freehand selection tool to add the pointers. I use an "Outer Glow" set to 100% opacity, 600% intensity, and 2-pixel blur to do the outlines. Borders can be used to distinguish between overlapping bubbles, also - see the top-right trio of dialogue. (I use two layers of word bubbles for that.)

I've seen some comics who give their word bubbles really thick outlines. I don't like that (unless it matches with the rest of their line widths, such as Penny Arcade), because it pulls them up into the foreground even further than the characters, or whatever the foreground is supposed to be. I set mine at 2 pixels to match the same width as the background lines' width. The bubbles' whiteness is enough to pop them out.

Note I've had to cover up some of my lovely books, but that's fine. Covering chunks of non-essential background is better than covering a character's head, or breaking way out of frame. (On a side note, I DO break a word bubble out of frame intentionally, just to break things up a bit, or to "connect" related frames... look for them!) The only downside to my "don't cover the character if I don't have to" rule is that one in twenty I'll have an awkward looking word bubble, that doesn't seem to fit into the overall flow of the word bubbles.

Also note that the word bubbles read left-to-right, as far as the conversation goes, as well as up to down. That's what I meant by "flow." The reader shouldn't have to figure out what they're supposed to read next. If I were in Japan, the whole comic would be flipped around, because they read right-to-left. Dialogue flow in a comic is trickier than you'd first think - I've made a few questionable word bubbles.

That's really it. I hope you found it interesting. There's a lot more that goes into a comic than I've mentioned here, but this isn't the Complete Theory of Comics or anything. If you want that, go get Understanding Comics. This is just what I do.