Picking a good spot is #1. I like finding a spot that's steep, then flatens out and then gets steep again. Build it back in the flat with a gap (however big you want) and then have the next steep as you landing.
This is a little exagerated but you get the idea:
Then your gonna want to pile your snow and start shaping. I like to use a bucket shovel that you can push like a front end loader but thats not easy to pack with you haha. This is gonna take a long time, you need to build/shape build/shape and pack it down... it takes a lot of snow.
Here's the key though. Once it's done do not hit it. Leave it for at least a few hours or even better leave it over night. The snow has to set or you will just crush it down or blast through it. The only exception is heavy wet snow, it can settle really fast when packing it down, still should let it sit for a while though.
You will probably still have to re-shape it a few times after the first few hits to adjust it and fix it up ect. Keep the transition really smooth, I like to shave it with my board from the top down holding my binding loops, best tool for the job.
Good luck! Hopefully some others can chime in with other tips.
- location, need a solid approach speed, and good steep but soft landing
- lots of snow, build in bigger than you think
- pack the shit out of it, add a layer, repeat
- sunny days help melt the snow a bit and it packs better
- make a solid transition