I'm still pretty new to the game (a year and a half in), and this was the hardest shot for me to learn.
First, recognize that turnovers and annys are a hard shot, period. Even the pros generally feel more comfortable avoiding them when possible. It's a tricky balance of release angle, release power, and release height to get the right kind of turnover/anny you're looking for. So first, don't discourage.
This was the first shot I really drilled. I would loop a set of four holes at my home course that all feature different kinds of turnover/anny shots repeatedly. I've put a good amount of time into learning this shot, and only in the last two or three months have I really started to get confident and consistent with them. And it's still relative: I botch the throw all the time, either turning over a disc too much or not giving it enough and watching it fade out in dismay.
So, practice is the answer, as always.
That said: the Underworld was the first disc that turned naturally and reliably for me. Back in March, when I couldn't get Rivers to reliably hold an anny line, the Underworld did exactly what I asked it to. It was a godsend, and opened up a lot of lines for my game. It was my doorway to a turnover show. Nine months later, I've gained about 50' in distance, and suddenly am throwing the Underworld much, much less. Increasingly, the River is all the understability I need. I'm not ready to ditch Underworlds yet - I'm pretty sure there are still shots I prefer them on, and it's just that my home courses don't feature these kinds of lines - but, your disc preferences often change, especially in the early goings as you increase your distance fairly rapidly.
So, if you're looking for a disc recommendation, mine would be the Underworld, in either plastic (Tournament will be more understable - at this point, I only really reach for my max weight VIPs, which are a bit more stable (but just a bit)). Beyond that, don't discourage, and realize that RHBH left-to-right shots are some of the trickiest in the game!
Good luck!