Remember that sunflowers will grow very tall and can shade out other plants if you are not careful. Sunflowers always point to the direction of the sun rising (east), so consider this when planting.
Soil types are not too much of a problem for sunflowers, although a well-drained soil with lots of peat, compost or manure will help them to grow tall and strong.
It is best to leave sunflowers where you plant them; if you try to move them, they will not really grow as successfully.