You're not doing anything extremely wrong, and yeah you're right about good players watching for sotf buff. You know what that means though? If they ARE watching for your sotf buff to interfere with landing cyclones....and you aren't keeping track of when you'll be able to get a sotf clone off (when stormbolt is on CD, not being in range of shockwave/pummel/disrupting shout) then they deserve to win that exchange. They are doing something extra that you are not doing.
I find it more reliable to bait out the reflects with a normal cast time cyclone. Unless I know my opponent is capable of reflecting/rupting the .7s clone, I'd rather just get the reflects out of the way early when I'm not under pressure to heal then my next sotf clone cast is more reliable since I don't have to worry about the reflects. Situationally dependent of course.
I've watched a little bit of pojke's stream when I started focusing on how to best use sotf (had taken tree form more during the beginning of the season). The play is so different, I have always played rdruid really offensively but that positioning puts you in danger of eating all the instant CC that is currently in the (meta)game and then falling behind. Pojke on the other hand, from what I've watched plays more defensively, uses sotf for regrowth when a cyclone cast isn't a high probability. If you think about it, it saves globals doing this, you're not wasting time or wasting the buff. I'm not 100% sold on that method being better, but it is easier and teaches a good overall lesson. If you can't get the clone cast off effectively at that moment, just use sotf for healing and keep going.
I don't typically use heart when say...a warrior pops his CDs. I will if I feel like I need to but I don't like to feel like I HAVE to use it every time some CDs are burnt. Depends on the comps and the moment and what other CDs your team has up. Always save skin/ward for the first set of DPS cds, and usually the person getting trained can help mitigate some of the damage too.