To some extent, deciding what to grow is a matter of trial and error, but it is a good idea to start with vegetables that are favorites with your family and also those that are expensive or hard to find in the shops.
List your favorite vegetables and decide what not to grow. Good-quality maincrop potatoes and cabbages may be available locally, whereas salad leaves, sweetcorn or early baby carrots taste better picked fresh.
Match your list to the available space and the time and energy you can devote to their cultivation. Recognize the difference between vegetables that sprint to maturity, allowing you to grow something else afterwards and slow crops such as Brussels sprouts that need a long growing season.
Use your space to best effect. Do you want to harvest a wide variety of produce for as long as possible or simply raise large amounts of a few varieties for storing or self-indulgence?
Find out what does well locally. As your soil and skills improve, your range of produce will increase, but some crops may not suit your soil or climate.
Keep a garden diary. Note your most successful crops and varieties, with their sowing or planting dates, to help you to plan for the next year.