Once you have decided on the style of your garden you can start thinking about the shape of your garden.† The basic themes are circles or more angled approaches such as squares & rectangles.† Its generally best to not mix the shapes too much as this can often confuse the eye.
The curves of a circular design can sometimes conflict with the harder edges of a more angled garden.† That said, there are plenty of examples where that can work well and its your garden so its down to your personal choice.
Draw your gardens outline and draw circles to define the key areas.† These areas could include a seating or patio area, a lawned area or a water feature.† Once you have defined the key circular areas then you can plan your planting around the circles.† Circles are very effective in hiding the shape of a rectangular plot and are softer on the eye.† Your circles do not have to be complete circles as it perfectly acceptable to have interlocking circles creating a curvy garden.
Diagonal shaped gardens can create a sense of space by taking the eye away from the boundaries defining it such as fences and walls.
Rectangles and squares
This is what most suburban gardens end up looking like.† Window overlooking a square or rectangle paved area to a lawn with borders down the side and maybe a shed or vegetable patch at the end.† These gardens are perfectly OK if thatís what you want and design it deliberately so.† However, often gardens end up like that because the owner has not fully considered what else can be done with the space.† For example, try offsetting the shapes to create a natural path for the eye to follow through the garden.