bomb #20 is a shitty place to learn wall jumping
op just keep practicing tholos
to answer your questions:
Some aim more behind them, some aim more in front. I know that you aim more in front as you gain speed but some people seem to be able to aim in front from the very start even when they aren't moving very fast.
The more forward you aim, the more your forward momentum will be converted to (limited) vertical momentum. As you're starting out, if you aim about 45 degrees back (so, if 90 degrees back is parallel to the ground and 0 degrees is straight down, 45 is down and back) gets you some speed and some height. 90 degrees back gets you speed, but because of gravity you won't be able to continue wall jumping, as you need to have some sort of bounce (like speed pogoing). aiming directly next to you or slightly ahead will result in less speed but slightly more bounce/height. And as you go faster, aiming ahead will result in the explosion occurring right next to you.
Also, when do you start to hold down the d key to strafe back to the wall? Right after you fire the rocket or do you wait a bit longer?
Play around with what works for you, but I press it immediately after letting go of A.
I'm trying to get across the large chasm in jump_tholos without landing on the platforms.
Just be careful not to hit the ceiling. I found that on tholos, once you get high enough on the wall to see the shadow line or above, you're risking getting too high. Hit the ceiling = kill momentum and fail the jump.