Replying to Booters

Hey guys i have been watching a lot of dvds were all the pros are hitting these massive kickers going like 100 miles an hour(not literally) but flying, anyways i have built some nice big kickers with my friends and i have hit some semi big jumps in parks what they offer but nothing to massive. I want to be able to hit them and do my corks, big spins, all my tricks on them but i feel like spotting is going to fudge me up, like over rotating or under, ect. anybody have any tips? how did you guys work up to it so i can?