Best free game out there I think, massively addictive, here's a few tips from my experience with the game

You don't need to buy the lunchbox's or bottles you can get them on quests and even more bottles later from bottle when he visits with cappy.

Post some guards with good weapons at the vault door.

If you build a radio room, even if it's for the achievement of build one of every room, don't set it to broadcast to the wastelands it just attracts more DeathClaws and out weighs the rubbish people it attracts.

When you send people out on long quests do it before you exit the game, the time counts even when your not playing.

The easiest way to lift the happiness score of anyone is to send them of for some sex, instant 100% happiness for the grumpy git.

Have fun, I'm sure you'll find loads of other tips as you play.