Hello there all Garen champion lovers here is mine favorite and most often used build and I hope it helps you out to reach at least Gold 5 in Season 5.

garen scales very well with AD runes and dat 1% crit chance can change the battle output. And MR and armor is always good in the laning phase.

21/9/0 or 9/21/0 Depends on your play style if you like aggressive laning go for 21/9/0 and if you are more a teamfighter person go for 9/21/0

garen is pretty much too OP with his sustain if build correctly and after a hard Tf you generate all hp in a few minutes and if the enemy chases you for a long time you can surprise them with your INSANE regen.

Pros
*Good sustain
*Good teamfighter
*Easy to carry the game
*Snowballs the lane very easy
*Easy to play

Cons
*If u do bad in lane you pretty much done

Try to focus the biggest threath to your team and ult him then he's low and after focus the enemy adc so your team can win the fight or you can try to protect your carries