Should I stay away from certain foods while breastfeeding?

No. Each baby is different, so if baby isn't feeling well (ex. More gas) you will have to experiment with eating different foods and watching for a reaction. Some mothers feel that their babies don't tolerate foods like broccoli, cabbage, and spicy foods. You may want to monitor baby's sleep if you drink caffeine or eat chocolate. Not everything makes it into breastmilk, however.
No. You may eat whatever you like while you are nursing; just get plenty of fluids, protein and calories. Occasionally, a baby may develop a reaction to a food you've eaten, usually a skin rash. Eggs, dairy, and nuts cause this most commonly. If that happens, simply eliminate that food. Caffeine, chocolate, garlic & onions get a bad rap. What you eat turns up in your breastmilk 4 to 6 hours afterward.
No. I don't think there need to be any foods routinely avoided by nursing moms. Everyone wants to tell moms what they can't have. That's not fair to mom-- it makes it your fault when your baby cries, when in truth babies cry for many different reasons, or sometimes for no reason at all. The only food *maybe* to avoid, for a short trial, if you have a fussy baby, is dairy, and maybe not even then.
Yes. I recommend no dairy as it is excreted in breast milk and can be allergenic. Other foods generally recommended to avoid include nuts, corn, citrus, wheat, and egg white because they can also be allergenic. I also let moms know to simply pay attention to what you eat and how your baby responds. Affects from food on the baby can be seen within 3-24 hours after eating.
No. Healthy, normal parents without food allergies can eat a balanced diet without needing to avoid certain foods. The diet should be safe; so thoroughly cook foods that may have bacteria or parasites, avoid foods that may have "slow viruses" (also called prions), and limit seafood to twice a week (choose low-mercury types of seafood). If the baby has food allergies, parents may avoid those foods.
No. It is best for mom to have a varied diet while breastfeeding. We see that babies do adopt the taste of mom's diet and that breastfed babies do later have a broader palate of foods! if your baby has colic, then we may ask that you reduce your milk intake or do a trial of elimination of milk, but for most mom's remember that you will need 1200 mg of calcium a day while nursing!