I researched and tested his build paths and this guide is a conclusion i made also there is a experimental armor pen build which i like to play against heavy armor teams.
HOW TO PLAY:
Blue side:Postion ur toplaner in a bush above the baron and dont want him to leash u.You will stand betwen chickens and river so u can see when u get invaded.

Red side:Postion ur midlaner or yourself bettwen chickens and river and postion ur botlane under drake bush if u get your midlane to stand betwen chickens and river u can camp with botlane to get some lucky kills.

After red clear chickens proceed to clear whole 3 camps and engage in crab then look if u can gank if not possible get fast through midlane to get second crab then look for possiblity for gank if not possible recall.

Explanations:
Why i play full lethality- Brief explanation on it why i play full lethal well cause i hate crit in general and i dont think its worth building it over lethality when u can get damage faster which is curently leagues meta for like 3 seasons i think so picking full lethal items allows graves for carrying faster and if u are fed u can help to fed ur teamates which will win u the game.

Start jungle-I dont take potions cause u dont need them to survive clear well u dont go over half hp at all so they are useless (Only good when fighting during a counter gank) Control ward gives u survilance of an important area like top side/Drake or one side of mid which gives u alot of information and ur teamates

Why dont clear krugs-They give u the most gold but cost u the most time which is really important at start of the game during this bonus time u can clear in good circumstance two crabs and gank two lanes which could actually win the game.

Trinity force build:Its a build i made along researching graves its biggest pros are kiting and tankiness with good damage also armor pen. and cons of it is mediocre build path for trinity force and slow power spike.I tested it myself and i found succes with it and curentlly with riot changing the meta in 12.10 this build has a chance to shine .

Why no invades: Thats beacuse people reading this guide will be beginers to graves so they wont try to invade when begining to play this champ if they will be intrested to continue playing him they will watch youtube to know how to do it exactly.