That's kind of a hard question to answer without a little more information.
Off the top of my head, I would say make sure you get enough rest, make sure your carbs and protein and fat are in a good balance, take a vitamin, drink plenty of water, and try to eat mostly clean (non-processed) food.
Your body will take time to get used to changes, if you're just starting out.
If you feel comfortable sharing a little more, such as your age, any heath issues, how far along you are in your weight loss journey, and what you are doing to lose weight, folks might have some more specific suggestions for you. Good luck!
"If you drop an egg, you don't say, 'Oh, shoot' and drop the other 11, do you?"
-Source unknown, but obviously brilliant
Reached goal 4/16/2010...but kind of afraid to look these days