First thing your going to need to get your head around is the idea of the Eclipse bar and the 4 stages you can be in. Pre Lunar, Lunar Eclipse,Pre Solar and Solar Eclipse. These pictures should help visualise the stages

Pre Lunar - You are building Energy to reach a Lunar Eclipse, you have no bonus damage at this stage. To gain Energy and move towards this Eclipse you cast Wrath. (Starsurge also moves you in the direction your already travelling)

pre lunar

Lunar Eclipse - You are now in Lunar Eclipse, when in this state you receive a minimum 41% damage buff to Arcane Spells + benefits of more mastery on Moonfire, Starfire, Starfall and Starsurge

lunar

Pre Solar - You are now moving out of a Lunar Eclipse after casting enough Starfire's/Starsurges and enter a phase where u are moving towards your next eclipse without any damage modifications

pre solar

Solar Eclipse - You are now in a Solar Eclipse and recieve a 41% damage buff to your Nature spells + more from Mastery on Wrath, Hurricane, Mushrooms, Sunfire, Typhoon and Starsurge

solar

Basically to move your Eclipse bar, you cast Wrath until Lunar procs and cast Starfire until Solar procs. Gets more complicated when your thinking of when to refresh Dots and also thinking about what Eclipse you want to be at a given time.

Starsurge

You want to use it to open with after applying both Insect Swarm and Moonfire then off cooldown from then onwards. You gain instant Starsurges with the Shooting Stars buff, use these procs as soon as possible. Delaying the use of it quickly could mean you "munch" the proc, which means you effectively lost a proc because a new one has proc'd before you even used the one you had. A Starsurge will also move your energy bar in the direction you are travelling when you use it, this might be working against you in some situations, more on this later.

Wild Mushrooms

Since 4.0.6 Mushrooms have become Very powerful, pushing boomkin into becoming the best AoE class at the moment, so get to love your mushrooms. Firstly, they benefit from being in Solar eclipse so try and be in Solar Eclipse when you know mushrooms are going to come into play. An example would be the add phase of Chogall, you know want to be in Solar Eclipse for this situation so you can prolong your Eclipse. If you never cast a Wrath or Starsurge you wont leave Solar Eclipse. Obviously in a single target situation this is a DPS loss but u could potentially gain alot by managing your Eclipses and maximising them in such a way. Detonation has a 10second cooldown however and it takes 3 globals to plant the mushroom, dont waste your free globals, always be either casting or spamming moonfire/sunfire.

Even whilst not in Solar Eclipse mushrooms are powerful, still worthwhile in a non Eclipse state or Lunar Eclipse, however if the mobs are likely to stay alive for a long period of time it would be more beneficial to multi Dot Moonfire spam all mobs, and work in a tripple mushroom explosion off cooldown.

Cooldowns

Starfall - Use off cooldown, maybe delay its use a little if your soon going to be in a Lunar Eclipse but at the same time you want it to use it as many times as possible during the fight, so dont wait too long

Tree's - Use off cooldown, try to pop moments before the pull to save yourself the global. They also benefit from bloodlust/hero so hold on to them forawhile so there out when its popped, dont wait for too long though.