Soil temperatures of at least 65 f will minimize the need for most protection from cooler spring weather. In cool areas transplants should be Protected with cloches or cold-frames as they are highly sensitive to frost.
Peppers require only moderate amounts of fertilizer. Pre-plant applications of dehydrated manure, followed by 5-10-10 fertilizer is a good idea. Cut back on fertilizer when the fruits set.
After fruit has set apply a thin covering of mulch for moisture conservation and weed suppression.
I like to spray my pepper plants with an Epsom Salts water mix, about one heaping teaspoon of Epsom salts well blended into every gallon of water.
Pepper plants also require sulfur, hot peppers more than sweet varieties, but sweet peppers also. Throwing some match heads in the ground with your transplants will help to supply it. Don't laugh, it's "cost-effective" and it works .
Disease can be minimized by proper spacing and by watering earlier in the day, so leaves dry quickly or by using soaker hoses / drip irrigation.