Step 1: Plant
Tomatoes can go in their own nice sunny bed and must have at least four hours of sunlight a day. But you can also put them in with flowers or in a big pot on the patio. (Soil in small pots usually turns to concrete). Try a cherry tomato in a pot in your office, by a sunny window, and offer the ripe fruit to passers-by!
You can either sow tomato seeds from a packet bought at the nursery or buy seedlings from the nursery. I'd do the latter if you haven't grown tomatoes before, so you know that those little darlings you're watering are tomatoes and not weeds that have sprung up instead.
Plant them about half a metre apart; water them with a light spray from the hose or sprinkler not a hard jet of water or you may damage them. Water every day or two till they're as high as your ankle and their roots are nicely established.
Step 2: Mulch and feed
It is almost impossible to overfeed tomatoes. That's why they spring up in badly treated sewerage and chookyards among almost pure manure. We picked 40 kilos from one bush once that had sprung up at the end of the henhouse in almost pure hen droppings. Then we gave up counting.
The more you feed tomatoes, the more you'll get. If you don't feed them, even if your soil is naturally fertile, you probably won't get a decent crop.
If you're a new gardener, just buy a complete plant food (an organic one like Dynamic Lifter is best) and use according to the instructions on the packet. I use home-made compost and old hen manure on ours, but that's a lesson for another day.
Tomatoes do much better if they are mulched. Mulch keeps down the weeds so you don't have to spend hours hauling them out and stops the moisture in the soil evaporating.
Tomatoes form roots up their stems and stalk if they are mulched. The more roots, the better they grow, so mulch right up to the stem if you can. I don't bother to stake my tomatoes initially the branches that sprawl on the ground take root, then I stake them up and have another tomato plant.
Step 3: Pruning
Don't bother to prune tomatoes. Tomatoes ripen in response to heat, not sunlight, so pruning off branches so they ripen earlier just doesn't work. Pruning is just one more task that gardeners have burdened themselves with. If you are a pruning fanatic, prune the tomatoes to two stems, or laterals. The lateral below the first flower truss is usually the most vigorous. But as I said, why bother?
Step 4: Staking tomatoes
Staked tomatoes look neat. Unstaked ones fall over and the branches sprawl all over the place, but sprawling tomato branches form roots on the bottom so the tomato vine is much more vigorous (if you don't mind wading through a couple of acres of plant while you look for ripe tomatoes).
If you are going to stake your tomatoes, use old stockings or bits of cloth rather than string, which can cut into the soft branches. Don't tie too tightly as you can cut off circulation as the branches grow bigger. Just loop the stocking round the branch very loosely, then loop it again around the stake. This gives leeway in windy weather so branches are less likely to snap if pulled away from the stake.
Step 5: Watering tomatoes
Try to avoid overhead watering it can splash disease spores up onto the leaves and increase humidity so fruit splits and fungal and mildew problems increase. Slip the hose under the mulch if possible or use trickle irrigation. If you must overhead water, do it in the evening (contrary to most advice) morning watering means they'll be wet in the heat of the day, which most disease spores love.
Another solution is to plant the tomatoes on slightly raised rows, then make furrows between the rows and water the furrows.