Play the standard maps (badlands/granary/process/etc) and practice jumps with the infinite ammo script and a button bound to noclip so you can reset quickly.
This basically. The best way to become familiar with maps is to just jump around them constantly. For rollouts, use the following script
mp_waitingforplayers_cancel 1
sv_cheats 1
sv_allow_wait_command 1
sv_lan 1
net_fakelag 10
unbind n
bind "r" "impulse 101"
bind "b" "mp_restartgame_immediate 1; wait 600; hurtme -160"
It will allow you to reset the map by pressing b and give you an automatic overheal. You might need to fiddle with the value of the overheal a bit since 160 is enough to give a demo 260 when leaving spawn, it won't be right for soldier.
If you want to become familiar with the map, infinite health and ammo and go nuts. If you want to plan for bombs though, do the following
bind x "hurtme -100"
with x as any key you want to give you the right amount of health so you can estimate the sort of jumps you can do when bombing in. With gunboats, health generally isn't an issue, but if you're going for insane bombs like doing a pogo rampslide on process, it can take more health than you might realise.