i like your Final itemset, but in slightly different purchase order:

Black Cleaver Sunfire Aegis Atma's Impaler Warmog's Armor Infinity Edge

or even more aggressive:

Infinity Edge Atma's Impaler Sunfire Aegis Warmog's Armor Black Cleaver

you should add some bbcode and more indepth-content (explain itemchoice in your guide, rune+masteries choice, ability.lvlup.order, your gameplay, teamplay etc) to make it more aesthetically, and update your cheatsheet with a Final Build, so that it appears in the Garen Build List Preview.

lead us to bronze Shablingows!

Be a Garen is being agressive at all times. Go go go forth and keep killing the weak guys that all game you wikl be OP. Garen late game will tank and finish low life champions. If he dies, probably your team is destroying a turrsnt or an inhibitor, because almost all the other one is dead too, if you play well. It almost always happens to me really. Keep that in mind. Be agressive since you see the other guy in the lane phase until you see the squichy guys lvl 16,17,18 in the late game.

Garen mid game is realy, realy strong so if u have sunfire and brutalizer (and boots ofc) your priorety should be destroing enemy inhib, if you do this the game is technicli winned. Now one important thing, to do this you have "2k gold" time, because after enemy get that "2k gold" and buy one-two items Garen stop being op :(