Another suggestion we would have is to use raised beds like this couple did. If you don't use raised beds,then you will probably want to test your soil to make sure it is not contaminated. If you are just growing flowers, you can skip this step. However, I would still test your soil even if you are growing flowers to make sure you know what amendments to add to your soil.
Personally, we love gravel because it gives the garden an instant cottage look. Other options are wood chips or mulch. If you are using grass, make sure that you leave wide enough paths to use a mower.