Cho-gath is a very nice champion, can be build as pure tank, tanky dps, or even pure ap if you want to have fun. I like him and have been playing as him for a while, in ranked play a lot also, so enjoy.

Cho-gath has a VERY versatile itemization path. There are so many different ways you could build him. My starting items are either boots/pots, doran's ring, or regrowth pendant and a mana pot. It all depends on my laning partner. If I'm gonna have to be dodging skill shots, like lee sin's Resonating Strike, or running away from scary udyrs bear form, then ill take boots. If I'm against very strong harass, I will probably take regrowth pendant for an early philo stone, and for godly health and mana regen combined with his passive. And then I might take doran's ring if I just wanna bully them, or if im going mid as Cho (which is very viable) Itemization for chogath is entirely dependent on the enemy team, and who you are solo laning against.

Here is a list of items I have used before with Chogath while being serious. Rod of Ages, Sunfire Cape,Banshees Veil, Warmogs, Rylais, Abyssal Scepter, Randuins Omen, Guardian Angel,Frozen Heart, Force of Nature, AEgis of Legion,
For boots, i will get mercury treads, boots of swiftness, or ninja tabi.

Also for teh lulz u can go ap cho mid, ignore all their harass and shut down their ap carry. OR go ad chogath with atmogs and wits end

Ok so ignore the sequence up top, because the beginning of skills all depends on what is happening level one. I don't even level up a skill at all while I'm defending blue, or wraiths, or double golems or whatnot, because rupture would be a lot more helpful for a level one teamfight then vorpal spikes or scream, though scream could work if you already have a taric stun to stop their flashing.

For summoner spells, I almost always take flash, then I will either take ignite or teleport. Teleport is a very good summoner spell for many top laning champs, since they are very far from the action, so they can teleport in for a crucial dragon fight or whatnot. I might also take teleport if I am laning against someone who I think well have very strong harass on me so I can take a beating, go back to base, and teleport back with more items and full health.

In the laning phase, I will almost never use q. I harass with scream and last hit last hit last LAST HIT. u need it for mana health and moneys. if you miss last hits cuz of e, turn it off, u sholdnt need it. I only use e in lane to harass and when i go head to head with them, because it pushes the lane, chogath is more good in lane at whittling down opponents, as he will probably have greater lane sustain. I usually try not to commit to extended fights, as most other top laners wiill either have shorter cooldowns or better atk damage for head to head encounters. You should come out on top in a poke war even with just ur w whenever it is off cooldown, just because you can run them out of mana.

Your ultimate feast should always be used to build up stacks in the laning phase unless you are about 80 percent sure it will land you a kill or you are about to get a gank. Another thing that is very useful abuot it is to steal the enemies blue buff. On my first or second trip back, I like to buy 2 or 3 wards, and put on at their blue, so I know when it spawns, and also ward my own river like a good top laner shuold. Then when i see their jungler and ap carry going bot or at dragon I can push my lane out and sneak over, grabbing a very quick blue buff. The 1000 damage to minions wiht your ult really helps with this. I do this in ranked play also, not every game but depending on how well Ive been doing. And if you see your lane opponent come to try to find you with you ward you should be plenty safe with you stun and silence.

Early game, you shold only farm with autoattacks and feast. Though once if you steal their blue buff, you can start throwing out ruptures and screams at your opponent, and it will make them very sad (and very low). Later in game you can take a full wave with an autoatk or two and rupture/scream. This also works with wraiths and wolves.

So during lanign phase as I said before you should really only use scream or spikes to harass, unless you get in a head to head fight. And unless they are standing still fighting you, never throw a rupture right under their feet; its just too easy to dodge. Rupture is really easy to hit when they are chasing you or another teamate, or runnign away from you. And remember in certiain situations you can hit rupture across walls.

Once you are farmed up and team fights are starting you should always lead your team and be the one to facecheck any bush if that is required. You will probably always be the tankiest person on your team, if you are playing right and have full stacks. The most fun thign to do is jsut chill alone with your team all in a nrearby bush. THey will eventually almost be forced to start attacking you lookking for the free klil. Tank all of their ****, especially if you have guardian angel and then watch your team swoop in for the ace. You probably won't even die.

Chogath's role in teamfights is a soak, to peel assasins away from your carries with rupture, silence the most annoying casters on their team at opportune moments (i.e when fiddle is channeling ult or such), nom to help finish low to medium healht priority targets. Dont nom their tank. Also you are just really big and annoyign and make it hard for them to select your teamates with spells or attacks because of your immense bulkiness.

According to any comments I will add more information that I might have missed or if anythign is requested.