Get some T3 flat Armour Runes for jungling, it makes it easier and the majority of junglers use them, so they're worthwhile investments!
Take your first skill as Drain, take a Dorans ring until you feel confident you can do without the health and start off with an Amplifying Tome and Mana potion when you get better at jungling.
Start at Blue buff and get a team mate to leash it for you. Always take Smite and its' mastery!
My rule: Don't start at blue buff. Double golems first w/o smite. You can get blue buff on at lv5 and solo dragon or have your team help if it's the right thing to do.
Why?
1. You get lv6 faster which is clearly good as you want your ult for great ganking.
2. Many people accidently restart golem causing them to die
3. For me, I gank fiddles if he starts blue.
Only for non-fiddle jungles, If they have a heavy AD team then you go for AP runes, if they have a heavy magic team you go for AP runes. The damage you minimize is less than the amount you heal with flat AP runes.
Drain everything, take smite.
Honestly Fiddle is probably one of the easiest junglers in the game.
Getting AP runes may be slightly better for Jungle Fiddles' drain, but I advise getting armour seals anyway for their wider utility, allowing Ray to improve his jungle with Gangplank, Ammumu, Nocturne and plenty of others who need that extra armour when their AP skills won't contribute to their protection.
When I said "some" T3 runes, I was referring to seals. I would of course advise getting specific marks+quints for ArPen/Dmg/AttSpd and MgPen/AP, but I believe if you're spending minimalistic amounts on runes, then armour seals are the default basic.