Step 1, buy Bandito Fiddlesticks skin.
Step 2, enter jungle.
Step 3, there were no survivors.
Tanking Fiddlesticks is pretty much 100% superior to AP Fiddlesticks in every way, for those who haven't played around with him much. Even before I completed my Sunfire Cape, their Warwick couldn't even try to touch me one on one thanks to Drain. By the time I had a full complement of Rod of Ages, Sunfire Cape, Spirit Visage, Sorc Boots, and Zhonya's Ring I could drain faster than any given one or two of them could damage me down. The only real thing about Tanking Fiddlesticks is he is incredibly golem hungry, but you should have golem as much as possible with Fiddle anyway for your ult unless there is someone on your team who can genuinely use it more.
Also, for anyone who wants to learn how to jungle, there is pretty much no easier character than Fiddle. He doesn't have a super strong level 4 gank, but he can punish overextenders with lizard slow, terrify, and drain, and if your lane has a stun or people who are on the ball it will be good enough for a kill. At level 6, he can and should punish every single overextender every single time his ult is up. Warwick is the easiest and generally strongest jungler for a team, but if you just want to learn, Fiddle is basically foolproof since you don't even need to buy armor items to start with thanks to drain, letting you start on a Rod of Ages or whatever else you want immediately. And while you should pretty much always take Smite on a jungler for general speed, Fiddle doesn't need it, which can sometimes give you a safe start at golem since the enemy team won't automatically assume you're jungling.
But as always with jungling, follow the golden rule; if you're not ganking or countering their jungler into a standstill, then you're pretty much useless.