Ganking as Master Yi

Hey guys. So, what with the release of the new project skins, I've been looking into playing Master Yi more--he seems to be in a pretty decent place, as far as assassins go (Rengar seems to have a bit more utility, but Yi can still do his job well).

I've been struggling with playing Yi, though, and I was looking for advice. Primarily, I play bruisers/tank junglers (who are very gank-heavy at early levels) and I feel as though that's part of my problem; worrying too much about trying to gank as Yi, when he's really not much good as a ganker (or at least, he doesn't SEEM to be--that might be part of my problem).

I'm trying to figure out when it's good to try and farm as Yi versus trying to gank--the conventional wisdom seems to only be to gank if you are assured a kill, because otherwise Yi is generally better off farming. Unfortunately, that leaves the question of what to do if your lanes are struggling--do you try and farm as Yi in that case, or do you give up stacking your devourer to try and go relieve pressure (wasting time on stacking your devourer, but helping your team get some breathing room)?

I also think part of the issue is my choice of summoner spell--it seems like smite/teleport is really the way to go on Yi, because it allows you to free-farm the jungle while still giving you the option to quickly respond to gank opportunities.

Mostly, the situation I find myself in when ganking is that I'm not able to kill the enemy quickly enough before they back off, and I wind up with no kills or assists, and then ultimately end up behind because I lost the opportunity for more sated stacks. Generally, my rule of thumb is to only gank when I have red buff and Highlander up--but even that seems like it doesn't work for me the majority of the time.

This may be just a skill-based thing, and the only solution is more practice. But if any experienced Yi players went through this and have advice on what to do, please let me know! I'm all ears. =)