well for 1, I would not normally help you learn a back flip over the internet.(parents frown on this stuff)
2 you are right in saying that it is a very comen question and a must in upping trick progres .
3 I should tell you to go join a club like Blackcomb freestyle and take the right steps
4 but im sure like half of us on this site your going to go out with some friends and try it anyway on some
But if I was going to tell ya, this it what I might say
1) make sure you have got it some where els. Just so you know what it feel like.(ie, pool,tramp,bed, rope swing)
2) Build a pow booter with a good landing
3) Make sure the jump has plenty of kick. Not some 30ft gap. Make sure you jump trany is long and does not super flex you ski . Just a nice 3 or 4 foot moggel kicker 5 feet to the landing. If at all possible make it like a table top not a step down.
4)Dont build it so far in the bc you cant get help, if your friend dives head first into your last bomb hole and checks out your Fd
5)Make friends with the kid that can so you can watch him first.
6)Fill in your bomb holes , not from the same snow in the landing
7)Text your mom tell you love her
8)DONT SLING THAT CRAP so hard you hit your head on the take off
9)DONT FORGET TO POP
10) POP,TUCK, SPOT, OPEN
almost every kid iv ever seen do a back flip ether sticks it or over rotates it the first time. Then they get all cocky and poop the bed on the next few because they stop thinking about.
So remember have respect for the trick or it'll get bite ya