Use the washer's gentle cycle. Slow agitation and shorter washes will protect your clothes (hand washing is even more gentle). Sort clothes properly and only wash with delicate items. Do not overload the washer.
Avoid the clothes dryer and hang dry if possible. If using a dryer, only dry for the least amount of time to lessen abrasion caused by other fabrics.
To remove pilling, carefully use a fabric comb or a pill/fuzz remover that shaves the pills from the surface of the garment. Only do this if necessary, and take extreme care while attempting.