I like ur build, my second recommended is what i use to use back in the day. Check out my guide dude. U will see our guides have fairly similar ideas :P

Vic10tor2,

Thanks about bamiäs cinder,forgot to change that. About pots.I guess im oldschooler,because I dont like bottles on any champion.Only on heca jungle. Maybe it will save you money,but they are stronger and you can decide how many do you need.

About masteries.Your Garen is perfect for newbies,and I played just like you.But when my skill advanced,my build also advanced.The main idea,is that your build is more safe,and easier in lanephase.My Garen stands harder in laning phase,so the early game is the hardest,and where you must show your skill. If you won = Snowball. And my Garen is stornger in mid-late game. As i wrote here,if you dont have enough damage,you are useless piece of meat.Somebody even dont get Black cleaver,and any damage,and running like 140 damage late game. My build is balanced,You can 1v1 almost any champ,and tank.Maybe my build is more off tank,but on Garen its Full tank.
=)

Thanks for the feedback m8 :) nice comment http://www.mobafire.com/league-of-legends/build/6-7-garen-giving-out-dat-demacian-justice-458031/discussion
my feedback:

Masteries i tried the ones you said before, I settled for the ones i use now. I think it's safer not to take the ferocity. merciless is actually a very strong mastery and goes well with your ult. Assasin is for lane phase and splitpushing, its a very useful mastery as well. Bounty hunter can give 5% but it is no guarantee and it will be stacked fully only at mid game if you are lucky. I think cunning has more to offer to our ball dragging demacian hero.

As for your guide, I like the way you play garen but in this meta you need a tank in your team always. If your comp has several beefy champs i build more dmg as well. Most of the time though i build full tank as your base damage is high enough.

Also bami's cinder is a better starting item than giants belt right now. almost never get boots fully built before your first item. When losing don't sink more money into regular pots, get the refillable as it will save tons. (do not upgrade it)

Your guide helped me think about stuff i still need to add into mine. IMO i still see some things don't aren't correct in your guide but no major flaws though.

You put alot of effort into it and it shows ;)

Great guide! Well written and fun to read. As a fellow Garen fan, I agree with what you are recommending and I appreciate that your guide requires some "Balls" as you say. :)