Laurence, we really need to know where you are. Here in Texas we are getting ready to put out tomato transplants--in NY they are getting tomato seeds into starting soil inside and with grow lights! Gardening is really different in different areas.
The only advice that applies to almost all gardens is: 1) find out what kind of soil you have, and if you can't determine that for yourself, get it tested through your state's agricultural colleges; 2) determine what part of your yard gets at least 6 or more hours of sun a day--veggies need sun, and 3) start thinking about what vegetables you like, and the amount you eat in a year.
If you are a beginner gardener, go with the gentlest fertilizer you can find--composted steer manure, or rabbit poop. They won't burn your plants if you over fertilize. Soil? If you aren't doing raised beds or container gardening, why buy soil--use what you have and keep improving it with compost. And that's another thing--as soon as you can, start a compost pile. And seeds--there are a myriad of seed companies selling on-line. Take a look at them and see if you want to spend the money on shipping. If not, a feed store, hardware store, or nursery will have seeds and be able to help you decide the variety you want to try.
Gardening is trial and error, but always fun and rewarding!
. What zone are you in ? We can help you better by knowing your zone.
