The best way to check if your soil is ready is to do a simple pH test.
Most vegetables prefer to grow in a pH range of 6-6.5. If your soils is below this, add lime following the directions on the bag. If your soil is 7-plus, add organic matter or iron sulphate.
When the pH is right, add a pre-planting fertiliser. Choose an organic one with plenty of potash, spread evenly, and rake in. You can then sow the seeds or plant seedlings.
To sow seeds, just sprinkle them along the row (they will generally germinate within a few days).
To plant seedlings, gently remove them from their tub or packet and tease the roots. Follow the instructions for each plant (including depth to plant, distance between plants and sunlight positioning), and make sure to carefully pat down the soil around them once finished.
Always water newly planted seeds with a fifth of a teaspoon of Epsom salts, or magnesium sulphate, dissolved in a litre of water to help activate enzymes and break down the food supply for the new plant. Keep this going until leaves have formed.
It's also important to water-in seedlings with a solution of seaweed extract and water. Seaweed containts vitamin B1, which helps overcome transplant shock and also results in a much earlier yielding plant.