Linework, linework everywhere and not a drop of space.
Seriously, was I allergic to blank areas? Why did I feel the need to fill the entire panels with busy details? It just makes the strip look busy and hides the important elements (the characters, mostly) among all the unimportant lines in the background. I guess it wouldn't be so bad if I varied the line thickness or darkness, but, with the exception of the thicker outlines around the characters (which maybe help some, but not really enough), I didn't. I think I did get better about this later. But maybe I didn't. We'll see.
Also! This was a particularly difficult strip to get the relettered dialogue to fit in the balloons. Between the revised version of the font not having exactly the same width and spacing, and the dialogue originally impinging way too closely on the edges of the balloons, I had to do quite a bit of cheating tweaking the font size and tracking. Meh. Well, eventually I'll finally get to the point where I'm drawing new strips instead of relettering old ones and then that won't be an issue (but then finding the time to draw all those new strips will of course be an issue... but one I'll deal with when the time comes).
(I could have redrawn and enlarged the dialogue balloons, of course, but again aside from the lettering I'm trying to change these old strips as little as possible, and besides that would involve covering up some of that excessive linework...)