it's definitely easier to start out doing them from a carve off your toes or heel. 180s off an ollie are generally done while buttering which you probably won't get into until you start to master your board control.
I find that it takes me 3-4 trips at the start of the new season to get back up to speed on what I could do by the end of the previous one. The big issue I had this season was hurting myself the first day out which has caused me to be a wuss the rest of the year. But I have landed more over rotated 360's this year then ever before.....now I just need to clean them up and stop being a puss whenever I take them to a bigger jump.
Me who just have learn to do some tricks on on the ground... wanted to practice them more... by next season, i certainly won't remember how to do it.
so much new fun things to practice but no more snow . can't wait for next season...
You can practice your 180s and 360s all summer long in your back yard. Just tape some cardboard (or something equivalent) to the bottom of your board and strap in. Alternatively, you can use some old carpet.
Concentrate on your technique. There are tons of videos out there about this (I like Snowboard Addiction's). I think it helps to use a full length mirror while doing this, so you can assess your technique. I do it in my basement.
You can work on ollies, nollies and presses (a little) as well. Just make sure to put some carpet down.