Olaf is a great champion and is a bit under used but I'm here to bring him back this guide is for jungle and solo top olaf or just tank olaf.i wasn't using him very much but then i started playing lol more and decided to play him again and realized just how good he was.

Pros

good jungler
very strong late game
massive life-steal late game
strong solo top
being a tank works well with passive
ult lets u avoid disables and take less damage

cons

slow early game
has slow but you need to land it
not the strongest early game

smite- a must have for all good junglers
ghost- makes ganks and escaping easier early game
teleport- when solo top allows you to back and get back to lane fast allowing for more farming

the runes i take for jungling are somewhat common for jungles but i take armor and magic resist armor more for early ganks and jungling and magic resist for the same the ad and as runes allow u to jungle faster heal more and gank easier.while the runes i take for solo top/tank are for what else being able to take damage and shrug it off and then go in and heal with your w

Most of the items you buy as olaf allow you to tank(i.e warmogs and frozen mallet)while having atmas allows you to do damage and still be tanky trinity force gives you AS AS and AP plus CDR movement speed and effect from sheen which makes your next attack do double damage after you use an ability although boot are totally up to you other then boots of mobility and sorcerer's boots.also bloodthirster is completely optional if you are doing really good get it it will add AD and life-steal but if your not doing as well keep wriggles it is a more secure form of life-steal because you need to get kills and not die with bloodthirster in order to maintain more life-steal

With jungling i always start blue and my w i get a leash and then about 5 seconds or so after blue starts attacking you hit your w then when hes low enough use smite then straight to wolfs at this point u should have e after wolfs go to wraiths then red and smite should be up again then proceed to golems(gank if your team calls for it or needs it if not continue) then i go back to wraiths then to wolfs then i back. after backing u should have wriggles and possibly boots if you ganked and were successful if blues not up at this point look for a gank if it is and no one needs a gank grab blue then begin ganking and pick up jungle creeps as you go and as blue and red come up and don't forget to ward and get dragon as early as possible use your team if you feel even the slightest bit of concern when going for dragon just to be safe