As you are level 34, I would concentrate more to the healing tree until you get Surgical Probe and the 1point sister-talent. You can get them by level 31. (http://www.torhead.com/skill-calc#401McfrzG0oz.2
) Then, if you want, you can go into Concealment to get the stealth-extras (I would still recommend full heals though, the 10 second boost to your stealth level via Evasion is good enough for stealth capping).
Basically what you want to do is always have at least 1 Tactical Advantage so you have the healing bonus. Only exhaust the last one on Surgical Probe in an extreme emergency. Keep your Stim Boost up (but no need to refresh on cooldown necessarily - the effect is longer than the cooldown so you can wait those extra 15 seconds), always exhaust a Tactical Advantage so you don't waste them by "going over three" (with Surgical Precision your TA-cap is 3, not 2). What I mean is that if you happen to have 3 TA's do not use Kolto Injection, as the TA that it grants wouldn't be applied because your stack is full. So at 3 stacks, go, for example, Surgical Probe -> Kolto Injection -> Surgical Probe.
Kolto Infusion loses a lot of its usefulness when you get Surgical Probe, but if you can spare the energy it costs and you need more healing than what Surgical Probe offers, you can still use it. It's also a good feint to use - if the enemy is aiming to interrupt your heals, they waste the interrupt on the "lesser" Kolto Infusion, which you will follow with Kolto Injection for more healing.
And as was said, use Diagnostic Scan whenever you start to drop under, say, 60% energy. Also use them as a filler whenever you don't need to really heal anything but there are still people with health under 100%.