So I have played a bit of Garen lately and this build rocks the house. I tried playing dps garen, ive tried playing tank garen. Both were ok. I loved trolling with tank garen cause he is pretty much unkillable because of his speed boost on q and his slow debuff removal from e. His r doesnt scale with anything so it does maximum damage with any build. DPS garen felt way too weak. Ive tried building him with the speed boots + 3 dorans blades as someone suggested in another build. It worked ok, but once it was time to upgrade and sell those dorans, it felt like i was throwing away gold and not gaining much in the way of hitpoints. Dorans doesnt build into anything and it also doesn't sell for a large amount compared to what you paid for it.

With this setup, you still get the early damage output as the other builds when you start with a longsword + 1 pot. You get some hp from the yellow runes so your early sustain is still good when you consider garens passive. The masteries are up to you, i take exhaust + ignite or I might switch one up for teleport for an early return to base when playing solo top.

As far as the items go, every item provides one of the following.
1. HP
2. Armor
3. MR

What makes this build work on garen is that every item also provides AD.

Also because of the way garen is being built, you can switch it up at any point in the game to customize the build to suit your enemy team. Have a lot of AD, get thornmail instead of hexdrinker, if they have alot of AP, get banshees veil instead one of your armor items.