Stay at max range as much as possible to make it harder for him to land his E on you. Getting too close to him will make it difficult for you to dodge and escape his Q.
Stand behind minions at all times so it is impossible for him to land his Hook Q. Avoid walking outside of the minion wave or in the open as much as possible.
Beware of Thresh’s gank setup as he can easily set up ganks with his W. If he walks near a wall, his Jungler could be approaching and waiting for the Lantern W before moving in.
Thresh will be looking for picks with his Q to start the team fight. Make sure no one on your team is out of position or too far forward as it may allow the enemy to start the team fight.
If Thresh misses his Q in a team fight, collapse on him and take him down. Thresh is really immobile and you should try to abuse him when he makes a mistake.
As Thresh will often go to ward alone, you could look to ambush him when he goes to place a ward. Taking him down early will leave his backline vulnerable to attack. You could also use the numbers advantage to take the Baron or Dragon.
Thresh is strong at level 1 in the right matchup and he can easily cheese. If you’re playing as a utility Support, take the long route to lane so he doesn’t kill you before you get to lane.
Once Thresh has both his Q and E available, his kill pressure increases. You should play more respectfully when he has these abilities available. The level 2 power spike, in particular, can get him and his ADC ahead if he is able to land a Hook Q.
When he has Boots of Mobility, his roam potential and ability to get ganks off well can cause problems for your team. Ping missing as soon as he recalls or leaves lane.