Prevention is better and cheaper than the cure. Strong, healthy plants that are well tended should establish fast and resist disease.
This is the place to buy stakes, bamboo supports, strong plastic guards against creatures, chemicals to feed and protect your plants, tools, gloves, organic compost and potting soil, and everything you need to get started by mail order.
Your first concern is to select plants that suit your soil, then prepare that soil to remove weeds and to improve its structure and "liveliness" with compost and other organic material: dig this in if your soil is light, or else simply break up compacted clay before planting, then mulch over the surface afterwards.