In general, avoid exposme to oil based paints, lead and mercury, all of which may be found in old paints that you may be stripping from surfaces. Also avoid other substances that have solvents, such as paint removers. Even if you're just painting a small room or piece of baby furnitme, be careful.
Work in a well-ventilated area to minimize breathing fumes, and wear protective clothing and gloves. Don't eat or drink in the area where you're painting. In addition, be extra careful if you use a ladder. Your changing body shape may throw off your sense of balance.