Thresh is a very underestimated mid, use this to your advantage. Thresh's abilities scale pretty decently off his ap, sit back and farm early on collect souls and get your gold. The souls are important because they give you an early ability power bonus because you have a chance to get ap while in lane. Don't try to trade hit for hit because Thresh's pull is his only ranged attack. Instead what you should do is wait until your opponent makes a mistake and capitalize on it. Hit then with your Q, a basic attack, then your E away from you and run before their cd's are back up. Thresh is SURPISING, the trick to his nuke is to use your E to knock them into your ultimate, ignite them give em a smack or two and watch em die.

Good luck fellow Strangers