-You basically want to play passive early game, which means last hit, freeze lane, and get free harass on the enemy if you can.

-Try to use the bushes to your advantage when you harass. You harass then walk into the bush so the minions don't aggro you.

-Try to farm near your tower let them push but don't let them push all the way into your tower. This is where thresh thrives. Here you are able to get harass, farm, and zone them from their cs. And if they try to engage on you from here you can flay them into tower or hook (depending on the situation and who you are up against). Usually this would force a flash early game. If he gets away with a sliver of health don't chase and burn your flash. you most likely won catch him. Just accept the trade and take his summoners.

TIPS:

try not to waste your hook. Most top laners would engage on you if they see you miss or know it's on cooldown.

After laning phase, Basically join team fights and make plays. Just don't try to hard to make plays and die for it.