- If they are giving you a puzzle, try your best to solve it. Do not be too worried if you can't solve it. Most of them will give you hints. I have been offered jobs when I couldn't solve their puzzles.
- If they're asking about opinionated questions (OSX/Linux/Windows, Git/Hg, Java/C, iOS/Android, etc), they are probably just testing your reasoning. It doesn't matter what you answer as long as you have your reasoning. Telling them you use Hg because your boss told you so is not good. It's always good to have a good lookout on new technologies.
- Go to meetups and talk to people. You will probably find a lot of jobs there. Be open, tell them you are looking for a job.
- Wear a t shirt and jeans. Drink lots of water and maybe a cup of coffee.