If you want to get free items on tf2, don't beg for them.
Go to a nice trade server (i.e not one full of F2P's).
Change your name to something along the lines of "Louis", and change your avatar to a nice pony pic.
Play around for a while, be a medic (not sniper) and be nice to people (if it's a peaceful trade server, don't kill anybody).
Pick out your victim from the crowd. Preferably someone who has a decent inventory. (use !bp where possible).
Send a trade request to your victim (i.e your "donator") and copy+paste a sad story into the chat, something about your parents dying in a car crash and how you're getting depressed and [what's left of] your family doesn't have much money. You get the point.
Slowly shift the subject towards items, and how you would appreciate it if they could donate some to you.
Then rob them blind.
tl;dr: make them sympathetic, don't beg