Play a game that's on sale. Do a new summer achievement in the daily games, get tickets, redeem for DLC.
I have four tickets as of now, downloading Lead and Gold to go after another.
Oh also, games are dirt cheap. You can buy EVERY VALVE GAME EVER (THIS INCLUDES PORTAL 2) for 50 dollars.
And if you own one or more of those games you can gift extras to your friends.
Topic: Steam Summer Sale- WITH A TWIST!