I'm assuming from a backflip.. You mean a backtuck? Backflip is what amateurs use and if you want one more step to glory use the right terminology haha. Anyways... Front tucks are way harder to land than back tucks do.
Anyways to do a good front tuck you got to jump and block til the point you are at your peak height! Don't rotate right away that is why people fail. Then when you reach that step you tuck in and let momentum carry you over. That is it. You don't need to prepare for this or anything just do it.
As for a back tuck get over the fear first before anything. Back bridges won't help and back handspring isn't really are pre. req. Just get over you fear and jump up, i mean way up until your at your peak, tuck, rotate, spot your landing and repeat.
Asking on these forums isn't what I would first do. Searching on google would produce better results.
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It is pretty aggravating! It will take time for some people, but not all.
QUOTE(diaperBOY @ Feb 13 2007, 05:58 PM)

ahh.. i used to do this.... its actually called tricking.. not free running (careful calling someone who tricks a free runner, they'll get pretty heated because there's been a debate on the differences between the two).. free running is also called : le parkour created by david bell .. here's the website i go to learn the tutorials: www.trickstutorials.com .. lots of flips , kicks, and twists if you want to learn.. it WILL take time though ... oh yea.. there isn't a tutorial for front flip