Hoi, thats gonna be my first build so please don`t be do harsh.

I´m gonna play Garen as a tank so the armor / magic resist runes are my first choice. I also use armor pen and atack speed runes / quent

I normaly start with dorans shield and go for boots than. I pick ninja tabi cause its cheap and underestamted in my opinion the chance of evade might seem low but it actually protects u from more dmg than u gues. Otherwis i would pick Mercur`s Treads or ionian boots, but i think u don`t rly need the passive from mercur`s tread cause judgment alrdy lets u ignore slows and the ionian boots are to expansive early on.
Next pick is Sunfire Cap or Force of Nature depends on what you are laning against. I normaly get both nearly everytime except the enemy team isn`t balanced with ads and ap champs.
Doran`s shield I sell when i need the place in the inventory or i miss just little money for completing something core
My fourth item is a warmog which gives u huge amount of hp which works just great with Atmas u go right after finishing your warmog
Atma`s Impaler is rly one of my favorit items its quite cheap gives u armor and crits ( judgment can do crits) and in my build about 80 dmg with its passive
( My last item would be an infinity Edge but honestly maybe one of ten games with garren i actually can build it so i`m considering getting some cheaper item in mid game)

I love exhaust use it with most champs helps u getting kills, avoids tons of dmg
Ignite i like cause it helps u against champs with strong lifeleech or hp regs

Those two spells fit in my playstyle and are my first choice , i just change them if i gotta go solo lane there i prefer teleport over ignite so u don`t lose the tower if u gotta go back shopping