Double Jungle works and it is extremely fun. Instead watching your teammate kill minions while you sit idle, why not support your jungler?? It can be a lot more effective!

Double Smite means you and jungler have the freedom to go for blue, red, or steal early on. It allows for quick gank and early dragon kill.

Slow plus Janna's W and Q means your jungler will have no problem ganking.

Start off with E so you can shield your jungler when attacking creeps. W will be my next item to slow down enemies. Q should come later because good players can easily dodge it. Q is more effective when escaping.

Pros
-Not your boring supporting role
-Gains assists fast
-Map dominance
-Enemy will be off guard

Cons
-Won't level up in beginning
-Success rely heavily on the jungler

Let jungler take everything so he can level up faster.

If no enemy jungler:
Blue>wolves>wraiths>red>golems>early gank or steal blue

If there is enemy jungler:
Wolves>blue>steal red (wait in their bush near red, then gank enemy jungler when he attacks red)

Your job is make sure your jungler is fed. Shield him when he is being attacked. Use your slow, W, and Q to help him gank. Buy lots of wards and oracle is a must so your jungler can roam.

Good jungle partners:
1.) Shyvana (strong damage and fast speed, squishy early on. Your skills are perfect for her).
2.) Yi (a fed Yi will seal the win).
3.) Shaco (Map dominance, surprise attack).
Any high damage champions might be good partner.