Now then, First of all. Your team will probably be against you jungling thresh. Now's your chance to prove them wrong! Head to wolfs, near blue. Wait for the appropriate spawn time, and get a good leash.(Damage) You want to use your flay as often as possible to maximize your damage and clear it the fastest.

So now you're at blue. Do the same thing pretty much, damage and leash and spam your Flay. Once killed, pick up a point in your Dark Passage and continue to wraiths after drinking a health potion. Start off by using your Flay, letting them hit you a little bit then use Dark passage. At the end of Dark passage, take a potion and continue fighting, using your flay when it is off cooldown. At this point you have a choice. If your smite is off cooldown and you have enough health, (I'd say about, 3/4 a bar will be enough.) Go and take red, using your Dark Passage when you take a bit of damage, Flaying, and attempting to use your chains to stun the lizard for a bit. then choose to gank a lane. Whichever is doing poorly.

No, that's not possible. But you ganked, Now what? Go back to the jungle, and do what junglers normally do. Jungle passively, while helping your team where possible. Not much to say really.

Play responsible!
Remember these tips,
1.A one for one is never worth it. (Unless that player is on a godlike killing spree)
2.Always expect the worst.
I cannot stress that enough. People go into 1v2s, almost win then say "Damn I ran out of mana" or "Dang heal is OP."
Okay, So thresh has two options once he's landed his chains on a enemy. Either use it again, If you're tanky enough and your team is backing you up to go TO the enemy, and immediatly use your Ultimate, Dark passage, Then flay people into your walls.
OR
Pull that ADC into your team, Flay him/her into you(Use flay behind your character) and then use your ultimate to do damage to any teamates who attempt to get to him/her

Now, Try to pull the ADC, and not the Amumu tank that can ult and just stop all your team.
This is my first guide, and is a WiP. Leave your criticism in the comments I guess? xD