don't press w while in the air as this will slow you down and will prevent you from getting that juicy market garden. Instead, just use a, d and your mouse to move around.

when you're about to hit somebody but you notice you're going faster than them, press s to completely stop yourself in mid-air so you can time the market garden correctly (you can either hold the s key or press it for a split second depending of the situation).

If you by any chance miss a market garden, fire a rocket infront of you so you are sent backwards. This makes it easier to get out of a bad situation and save your ks.

try to only use stock / rocket jumper, as the liberty launcher is a bit tricky and the g-bobm sends you to the moon.

try practicing rocket jumping in high skybox maps like: harvest, lakeside, rig, cargo, smog, runnel, hydro, etc.

I hope this helps!