I am lvl 21 druid, what tree should i go under to make lvling go by faster, I am a first time druid player, i love the cat form nice damage. Any help would be nice...

What I found to be the easiest for solo lvling was feral. I then respecced to balance at 40 for the Mighty Moonkin.

Feral for leveling and then respec at 40 if you want to. The thinking is that Balance are just too squishy untill you get the moonkin. The resto's will tell you that resto will give you more survivability but for me it's feral for the quick killing and leveling.

Really depends what you like to do.

If you enjoy cat form you will probably level fastet full feral (14/32/5), if you like grouping and grinding the same instances over and over resto might be for you, or if you enjoy throwing spells around go balance, but balance is easier after 40.

This is my first druid and I've been leveling fastest out of my group of friends who've started at the same time. Closest one is a warrior who is about 2 levels behind me at the moment.

I went with feral right from the get go. I would suggest either the 14/32/5 build (or using it to level up) or the 0/30/21 build. Sure you can respec once you ding 60 but when you're leveling, I would suggest filling out the feral tree first (if you're using one of these builds).