Leave a +rep comment on my profile, preferably a more elaborate one, not just "+rep nice trader", but more like "+rep Best trader I sold him a knife, went first and wasn't disappointed. All smooth and clean". Feel free to add suggestive emoticons.

I'll make sure to +rep you back within 24 hours, most likely with the same comment you left on my page. Add me if you wish.

Examples to copy&paste if you have no ideas (although I appreciate originality and prefer long comments):

+rep, I recommend him as a trusted PayPal trader
+rep, sold knife for some real cash, went firs and wasn't disappointed
+rep, best trader i sold knife to him I went first. All smooth and clean.
+rep, knife trader (Paypal), I went first. TY
+rep, trustworthy real money trader, will do business with him again soon
+rep, trusted trader I went first and got my money
+rep, sent my knife first got my money
+rep, great trader I went first with PayPal
+rep, trusted PayPal trader, I went first
+rep, sent him the knife and got my money
+rep, fast PayPal trade. Trustworthy I went first
+rep, great, highly recommended !
+rep skillful businessman, very patient, great communication

+Reputation. Concrete, nice and most important LEGIT buyer. Sold my high tier Karambit for €700 @ PayPal "gift" option. All went in like 30 seconds. Fast and smooth. Regards mate.

+Reputation, I went first with 65$ ... and he gave me 50$ on paypal :) Trustable person... I really like this man :* love ya

+reputation, sold him my karambit 90/7/3 FOr 500€. VERY GOOD BUYER. He Told me he was not going to Go first So I had to trust him because I really needed some money. Went first, got paid in an instant @PayPal

+rep, I went first with my money for 48 keys and he traded me the items afterwards so this guy can be trusted whether you're going first with money or items. Good and trusted buyer, i'll come again, nice prices and good deal.

+rep, just sold him mine flip knife doppler for real money via paypal gift. i wasnt sure about real money transactions.
i saw his very nice reputation here on steam and high reputation on ♥♥♥♥♥♥♥♥♥♥ and i have decided to trust him. i was scare at the beggining but after i sent him knife, i get my paypal money after 1 minute. he gave me good price and was kind and understanding to me. actually he is real good mate and a buyer. thx

+HUGE reputation from me to this guy! Couple minutes ago sold for him my Karambit | Case Hardened (MW) with like 50% blue pattern on playside! Fast PayPal transaction, without any problems. Got money quickly and straight pump my Steam Wallet with his money. Easy trade, fully trustworthy and kind person and buyer. That's all what I wanted to say about this guy. 10/10.