Aside from being a fantastic nuker Annie also farms/pushes very well. To farm well incinerate needs to 1 hit the ranged creep wave, which is significant when the ranged wave has like 10 creeps in it and you clear it instantly. She can't do this without ap and +ap runes help push you past the damage threshold
To help you do this, i take Ap/lvl runes in blue, manaregen/lvl runes in yellow, magic pen runes in red, cd reduc in quintessences.
my mastery build has 4 points in the exp boost, 2 points in the creep buff bonus and 3 points in mana regen. I have mana regen to help harass better in lane with incinerate, netting one or two creep kills along the way.
unlike most annie players, i don't get one level of molten shield. I feel that it hinders the early burst somewhat and you can get stuns charged with good cooldown awareness and timing. Thus spell priority: Tibbers->incinerate->disintegrate->molten shield
summoner spells: flash and exhaust. Flash gets you out of painful aoe effects, into the range of heroes far away in team battles (like twitch), over walls etc etc. For this reason i dislike ghostwalk because it doesn't allow you to do any of that. Exhaust>ignite because at early games i use exhaust to slow targets down for tibbers to hit. People underestimate how much damage the **** bear does and i get plenty of kills thanks to a bear last hit. Also exhaust is so much better in lvl 1 fights.
LEARN BEAR MICRO. hold alt to move your minion, so tell tibbers who to punch
I ask for mid solo whenever possible. hit 6 asap, teleport home, or wander off into the bushes. Either their mid guy calls ms and everyone hides (which benefits your team) or no one hides, you walk into either top or bot and score a double kill. This really, really benefits your team because one lane suddenly opens up and you just might get a tower kill. Otherwise, if at 6 one guy is dead/pushing the tower is difficult, use the bear to go kill golem. micro your bear, stand like maybe in the river (or an equivalent distance) while you walk your bear up towards the creeps. The creeps will hit the bear instead of you, so he's tanking. The bear doesn't need hp because as timing goes tibbers will die approx 10-20 seconds after you kill golem, leaving you with practically full hp (topped up with pots) and a golem buff. Get back in lane and start throwing spells at your oppisite number. Again timing: golem buff will last you long enough to get two quick tibbers, if you use your tibbers to gank the minute it's up. with your second tibbers you can get another golem etc etc
In team fights, either your opponent has lots of veils, or no veils. Either way, I advise hanging back, unless you have a ****ton of AP and you're willing to initiate with bear stun. Hold your ulti while energised: a well placed stun will easily win you the battle when you stun 3 people for 1.75 seconds and 600 magic damage. Tibber's immolation aura is seriously painful and can increase your damage output even more. Alternatively, save your stun for the dps carries, most of whom you will 3 shot with tibbers->incinerate->disintigrate.
In team battles, use the following rotation: Tibbers(stun)->incinerate->disintegrate->shield->disintegrate->incinerate(stun) as much as you can. The first 3 spells come out in an eyeblink anyway, but this ensures that your next incinerate stuns in an aoe, which can really be the difference.