I will not force you to write a comment but please do and tell me what's wrong : )
thank you

Many people like to max their pillar of flames first but in my opinion conflagration is better early game for farming minions and harrasing enemy champion.
while pillar of flames has slightly more damage you can use it to put enemy minions ablaze and when the enemy champion comes in range use your conflagration for the AoE and this way you can damage them alot early game which will make it almost impossible for them to farm.
Brand is also very good in team fights because in my opinion he has the best AoE in the game.

Brand depends on his combos alot so remember this:

Sear - When target ablaze it stuns your enemy

Pillar of Flames - When target ablaze it deals 25% more damage

Conflagration - When target ablaze it becomes AoE

Pyroclasm - Brand ulti goes alot faster when target is ablaze

Sear - is great for when chasing down enemy champions, use your ghost and put the enemy ablaze with your conflagration which will stun your enemy and probably get you a kill.

Pillar of flames - great spell for takedowns and also to put multiple enemies ablaze and give you advantage for when your enemy comes near one of the minions to use your conflagration and hit him.

Conflagration - In my opinon this is brand's best spell with his passive, because after using pillar of flames you can use conflagration and farm very good. and the best thing about this spell is how you can completely dominate your lane so your enemy won't be able to farm.

I suggest starting with a little bit ability power and a potion just because it helps.
then shoes give you speed and magic penetration which really goes well with passive.
then a hextech revolver in my opinion is a must because it really helps you stay in fights early levels so you won't have to go back so much.
tear of the goddess is also very important because you want to be able to cast a lot of spells and brands spells require quite a lot of mana.
rabadons deathcap is just the kind of item that every abillity power character must have because it gives you so much damage on your spells. than if you still want mana and you have the money get archangles staff because it's just better like that ^ ^.
void staff is very nice too and really goes fantastic with your passive. after that you would want to aqquire zhonyias hourglass (you can actually get it before the void staff, your choice) because after using your combos you can use it untill the cooldown ends and there you go ready to fight again.
and last you can sell your revolver and get a rylais crystal sceptar for a little hp and the slow helps alot

Pros

High burst
Great farmer
Low cooldowns

Cons

Very squishy
Usually targeted first

The hextech revolver is not a must!!!! you sell it anyway and in my opinion it really helps you early game