I am a wannabe healer. From my days prowling Paragon City and even before, it was all I really wanted to do. Call it a Character Flaw. Here, healing is a rather specific speciality that requires skills mastery and Situational knowledge. The Latter can only be learned by actual experience - Jump over this cliff (What? why?- you think but can't ask) or Stand Right here or O yeah, don't touch that. That kind of thing. It's pretty specific and while I've read a bunch of guides, there is no substitute for the actual experience. That said, If you don't have this knowledge, your charges bleed and die as do you. It's embarrassing. It seems to be the nature of the education though. As I say, only experience can give you that half of your toolbox.
The other half, the Mastery of your particular skills/powers, well those need practice too but there is a simple proving ground where you can see what you can do in a less consequential but really chaotic and realistic situation.
SHAMBALA.
There are times of the day where one can sign up, Play the match and return to where you stood in under 4 minutes now in possession of 2k and 3 loot bags. Then turn around and do it again. New skill you want to try out? Try it. Didn't work, Try it differently or try something else. It's not a dungeon or a raid, it has its own specifics- the field will try and kill you- but it's not that much to learn situationaly.
WHAT I DO
Understand that the teams are really random and unless an ODO member is on my team I don't know anyone, nor they me. Like a Cavalry charge, the battle is often worn or lost in the first 20 seconds. I usually pick a team mate -who I might know as a survivor of prior PVP battles- who I strive to keep alive. It may be a tank or just a random stranger. I treat them as I would my Tank in a dungeon. If they notice my heals and are on their toes, they realize my value in keeping them upright and circle around to my aid when needed. Agro from players is not like dungeons either. Ten seconds in I have usually Shielded that player as best I could , healed their initial damage and thrown something onto the rest of the team. Ten seconds after that, in the chaos of battle, I am targeting specific team mates and still healing my charge. I run through about every heal I have in that first minute. If I'm still alive, and if they are, I stay with it but chances are some have fallen and as often as not I have too. If I'm alive after 60 seconds I'm probably being protected and we are probably winning. If I die, I've usually done around 100k healing, If I live, Usually more than a quarter million - and sometimes more than half a million. It is great chaotic fun and I feel much more knowledgeable as to my skills. At the end, everyone on both sides has their stats displayed as to healing damage and such. It is useful to measure what worked and what didn't. I can't speak for anyone else, but as a training tool, I feel it benefits me a lot. Usual time from signup to finish: 5-6 minutes.