As you would expect from their name, sunflowers like a lot of sun so the place you plant them needs to have as much sun as possible for them to soak up.
They like well-drained soil, so add a bit of compost to your soil before you plant and make sure there’s plenty of depth as the roots go deep.
Allow space between your sunflowers plants so they have room to grow, they need space for their roots to spread out horizontally as well. The best advice is to plant your seeds (or seedlings) at least three feet apart.
Most sunflowers get so tall they will require staking to support them upright. A tall bamboo cane will do nicely, or if you have them planted along a fence, you could tie them in place with twine.
You can grow sunflowers in containers, but it’s best to stick to dwarf varieties in that case.
Unfortunately, slugs love sunflowers. If you do suffer from slug attacks, I heard a nifty trick from organic gardener Jean Perry recently. Try an upturned grapefruit shell, left over night – it will be full of slugs in the morning, that you can move/dispose of as needed.
Alternatively you could try organic slug pellets, which are safe for use around children and pets.