I made an account just to show some LoL players who didnt manage to get the hang of Lee Sin or Renekton.
I must mention i never had a low kdr with these 2 builds and always had under 3 deaths; usually my kdr is somewhere >4, and my assists are way more that my teammates', except for 1 time when in my team 2 players decided to leave and had a score similar to 3/5/7.

Well, its not hard at all to explain what to do when laning:
Q is your harasser and also your best last-hitting tool, along with E and R.
W is mainly an escaping skill - just target and ally and practically flash next to it, and also it can be used as a health replenisher in combination with E on a wave of minions or Q on a high-hp creep, since its dmg is lost-Hp% based
E is a large-area slow for when you have to initiate fights (although i dont advise you to do so) or for instantly slowing enemies while chasing them
R is your finisher move or your escaping skill - youll just roundhouse-kick all your troubles away ^.^

Most important- take advantage of your passive at all times + time your skills correctly, dont just spam them or you will end up in a fight with no energy.

PROS:
nice dmg spam
nice last hitting tools - Q , E, R
beefy champion, will be able to tank pretty easily most enemies
massive slows E + your Frozen Mallet will cripple the sh*t out of any enemy

CONS:
sometimes hard to last-hit, since your Q is pretty hard to aim with
a synchronized chain of CC can finish you pretty quickly

Q is his healing skill and also his finisher
W is the best initiation tool; just stun your focused enemy away! xD
E is the best way to approach or get away from enemies, and its also a very good farming tool late-game
R its your escaping skill or your initiation skill, just pop it up before a gank or a teamfight
PS: dont waste it on 1vs1 fights unless you need the extra HP

PROS:
tanky
nice last-hitting tool - Q
good dmg output
good CC spammer

ps: i use the same runes and masteries with renek and lee sin