Each year, if you are planting a veg from one of above groups, it needs to be planted in a different bed from the previous year. The best way is to draw a plan/take photos and compare it with last year to make sure the crops are rotated. Salad vegetables should also be planted in a different bed each year. A plan helps to decide how many of each veg to grow and track the crop rotation from year to year. By moving the crops around you will reduce the incidence of disease, which can be a problem when growing vegetables, particularly in wet summers.
When planning the veg plot, don't discount last year's seeds. Seed is increasingly expensive and for some vegetables such as courgettes, a couple of plants are often enough, and often last year's seeds will be viable and it is always worth trying to germinate from the previous year's seed. It varies from seed type to see type. Ideally if you are storing seed over the winter put in a cool place in airtight tin, the fridge is ideal if not a cool garage.