Not Updated For Current Season
Renekton - for the playing impaired
First let's look at your skills not in overly simplified terms:
Q: AOE dmg with health regen a percent of the damage. I max this first (I know, Noob!) because it helps you lane longer without having to go back if you're careful. Also if you hit a hero with the aoe the dmg and heal are increased so try to hit heroes with this.
W: Stun. Pretty simple, pop it and attack. First thing you attack takes double damage and is stunned.
E: Blink. IF you blink through an enemy you can blink again.
R: Nasus' Ult again. You get more health and do magic damage/second to nearby enemies.
Gameplay: Grab your ruby crystal. Pick a lane. Farm. I'll usually go into the woods, hit my stun, go attack once then use Q and run away back into the bushes. If your teammate is any kind of good he will pick up on what you're doing and help you harass when you go to stun. With this runes and masteries plus ruby you have close to 850 starting health which is very high. Run in between the melee and ranged creeps to pop your Q in order to get the greatest amount of damage/heal. When you have enough for boot and to finish one or both of your first Hearts of Gold, do so.
With the Greed mastery and two hearts of gold plus the experience boost from your masteries, you should be able to basically do absolutely horrible and still keep pace with the rest of your team. Finish your boots next, with, as always, boots being situational. If the team composition is mostly casters I'll get berserkers greaves to synergize with Frozen Mallet.
I found that there are numerous guides to pwning face with Renekton. I've been playing with Renekton and found that all of these guides are probably very good if you have played him enough to understand how he plays. Renekton is a pretty tough champion in my opinion and he isn't a hero you can just pick up and win with. To that end I present my guide, the Renekton "you can live long enough and make enough mistakes to begin to understand how to really play him" guide. IF YOU TRY THIS BUILD IN RANKED PLAY YOU WILL GET LAUGHED AT AND BEATEN TO DEATH This is not a PRO guide and I am NOT a pro Renekton player. This is the build I've been using lately that allows me to get a feel for him, remain competetive, and still be useful to the team.
I go armor pen reds because even though they keep getting nerfed, they are still better than most other options. Renekton's skills do physical damage afaik so they benefit early game from the armor pen.
The yellows and quints I take health per level and flat health respectively. I feel that he really has a very weak early game so the added health will keep you laning for longer.
For blue I go magic resist but I could see doing armor if you feel like you would like to do that.
My main goal for runes is just to keep me alive for as long as possible levels 1-9ish.
Start with a Ruby Crystal and build to two hearts of gold. This should not take you too long. Renekton's farm is pretty good, using slice and dice and cull of the meek to farm and heal yourself. Boots are, as always, situational. Get whichever you feel are most appropriate.
Handy boot guide. If the enemy team is x then get y:
Attack Damage = Ninja Tabi
Casters or CC'ers = Mercury treads
not doing well = Ionian boots
Squishy ranged DPS = Berserker's
Berserkers will synergize with Frozen Mallet, your next item, very well preventing heroes like ashe or caitlyn from just kiting the hell out of you.
After you have Frozen Mallet, mid game should be in full swing. You can finish up Randuin's Omen from one of your hearts or work on sunfire or Guardian Angel whichever will benefit your team the most.
I will usually get Cull the Meek or Ruthless predator first. I just won't choose and see what my teammate wants to do. If he is in the ganking mood I'll grab the stun. Otherwise, grab cull the meek and go.
I know. I know. Maxing Q first is uber noob. But this is a guide for Renekton first timers. Q will keep you in lane for a long time as long as you don't let yourself get harassed to very low health. If you DO get down low and you're level six you can use your ultimate. Using it and letting it run out will put you back at half health which should be enough that you can heal yourself to full from there.
Your ultimate. Eeee. So far, and I only have about 400 wins in non ranked games (Ranked makes me rage too much), so I may not be the best judge here. But....I feel he has the worst ultimate in the game. It's like Nasus' only worse. It gives you some health but health is so easy to remove and the amount it gives you is pretty much a pitance anyway. It has gotten me out of some scrapes before but it just isn't that great I find. Use it before you initiate or if you initiate and you're getting swamped. Pop R and then dash out making sure to hit a creep on your way so you can dice again quickly.
Slice and Dice is a great little escape mechanism and this is one of your assignments. Go find the walls you can dash over and which ones you can't. It CAN cross walls but only extremely short ones so it really takes some practice to learn where you can and cannot go.
Ghost and Exhaust. Fairly standard. You can put ignite or flash in if you're feeling plucky. I find it doesn't really matter as he has his own escape mechanism built in with Slice and Dice. If you Really get in a pickly ghost can usually help you out.
I'm not a super pro but I've been using this build for the last few games while I learn Renekton and even though I've done some stupid *** things, I have been able to end with a positive KDA most games. I'm still figuring out the best way to use his skills and how he synergizes in a team, but not a lot of people play him I find so it's hard to watch others and see how he is built/used. Hopefully with this build you'll be given some leeway to experiment a bit without putting your team at a total disadvantage.