Inoculate the soil with beneficial bacteria called Rhizobia to promote root formation that helps convert nitrogen in the air to a form usable by the plant. Go easy on fertilizers. Thin after plants are up, to 2'' between plants.
Additional fertilizers are usually unnecessary and tend to produce a lot of vine and few peas.
Mulch with partially decomposed compost after soil has warmed, to prevent weeds, keep soil cool, and provide disease protection. Water lightly until peas begin to flower, then keep soil moist as the peas fill out in the pods. Be sure to water from below, keeping the foliage as dry as possible to help prevent disease. Check your plants daily and pick the peas as soon as they fill out the pods. Peas left on the vine become starchy and reduce production.