Finding a bonfire of your own faction and speaking to the appropriate NPC will reward you with 5 Burning Blossom and 5 gold 95 silver at level 70.
Finding a bonfire of the opposite faction and using it will reward 10 Burning Blossom and 11 gold 99 silver at level 70. All opposing faction bonfires may be doused without pulling guards, but the bonfire in Wilhammer Stronghold in Shadowmoon Valley may be doused without pulling guards only if you have a flying mount or can stealth to the fire, making this a fast and easy way to generate Midsummer Festival currency. Dousing another factions bonfire will flag you for PVP combat.
The bonfires of Capital cities have separate quests and you cannot 'Honor the Flame' of your own faction's Capitals.
As there are 32 Alliance Fires and 30 Horde Fires, you can get as Alliance 550 gold 10 silver and 460 Blossoms, and as Horde 562 gold 18 silver and 470 Blossoms, not counting quests or capital bonfires.
Pics of locations are as follows
Also note to get the crown of the fire festival you need to be level 60 and loot all the flames any level can loot them but only if your level 60 can you start the quest at a festival talespinner.
+Rep helpfull guides.