I spend a decent amount of time talking about dialogue. The reason is simple: it’s important. It’s what the reader is literally reading. So a lot of words have been and will continue to be spilled about dialogue.
However, not a lot of words are said about lettering. It is not as simple as throwing words on the page. A lot of work has to go into making it both look good and read correctly, and it starts with the artist.
A good artist will read the script and incorporate the dialogue placement into their proposed layouts when they’re doing thumbnail sketches. There are a lot of artists who don’t do this, and it forces the letterer to make awkward and even sometimes bad decisions when it comes to putting words on the page.
Now, a lot of writers will try to save money by doing the lettering themselves. This is very often a mistake. Bad lettering has killed a lot of self-published books that otherwise look good.
If you feel you just can’t afford a letterer (then you really can’t afford to be doing comics, but that’s a different discussion), here are some things to keep in mind.
The words inside the balloons should form a diamond. A few words on the top line, more words in the middle line(s), and a few words on the bottom line. The reason for this is in order to use the space as economically as possible. You don’t want to have more space than you need.
Kill all crossbar I’s except for the personal pronoun. Think of it as a search and destroy mission. Treat it like Pokemon: gotta catch ‘em all! Nothing says “amateur” quite like a mixture of regular I’s and crossbar I’s where there shouldn’t be.
Don’t let the word balloons crowd the words inside. There should be about a letter’s width worth of space all around. More is too much and less makes it look crowded. (There are times when this “rule” can be broken.)
Make sure all balloon tails come to sharp points. That point should be about a third as long as the entire tail.
The balloon tail has to point to a mouth. Not to an eye, not to an elbow, not to a leg. A mouth. You see a lot of this in self-published work, and it’s a very easy fix.
Try to anchor the balloons to the top of the panel border whenever possible.
These are very simple tips that only begin to scratch the surface of lettering. If you incorporate them, though, your books will start to look that much better.
(And I still suggest hiring a letterer. You can get a decent letterer at a decent price that will not break your bank.)