Formal
For many people, a formal garden conjures up visions of large-scale formal beds, symmetry and regularity, but in reality, a formal garden can be achieved in a garden of any size.
Why not create a small-scale knot garden by establishing planting beds enclosed by box hedging, or if your garden is even smaller or a balcony, then position standard bay trees in containers by the garden entrance?
If you have the space available then you can be a little more ambitious and include the classical features of a formal garden by establishing a clear structure, geometric shapes and a symmetrical flow. Plants wise Buxus, Taxus, Lavandula and Laurus immediately spring to mind but don't forget the flowering splendour of Roses, Hydrangeas and Lupins.