Mix it properly so that all the level don't sit on the red, it's okay for it to go there every now and again though (This is what i'd recommend). You could however just slam a limiter on the overall track (the output track or something similar) and that will level out all the volumes but make the quality worse. Try both, see which works better otherwise I can't help you, sorry dude.
on Siren - Kick Build Up by mimerfly
Peace.