Patterned paving has long been popular in gardens. The Romans admired it greatly, extending the feel of their mosaics into outdoor areas. You can use pebbles in small courtyards to create colour and interest, even when there are few flowers on display.
To find inspiration for this type of design you could consider the designs of Renaissance Italy, for example at Villa Giulia or Villa Farnese, or in more modern times Paul Bangay in "The Boxed Garden" (Viking).
Good contrast in the colour of your pebbles is essential for pattern effects to read well. It's much easier to calculate the design before you start to work in the garden. Designs should be symmetrical, and it's a good idea to include an outer border. At this stage, think about the colours you can incorporate into your paving. White pebbles make a superb backdrop, and reflect a lot of light into the garden, against which you can use black pebbles for pattern. If you have a lot of light already, you could use dark pebbles as a setting for white.
Measure your site and draw it up on graph paper. Allow 10mm on the paper to equal one metre on the ground. Plot your design on a piece of tracing paper placed over the graph paper. For a symmetrical design, you can then turn your tracing paper over, and draw over the design, to transfer it to the graph paper.
Designs could consist of formal patterns; say a checkerboard pattern, or concentric circles. Alternatively, use a flowing pattern. Ensure that the curving lines you create are broad enough. Thin lines look too fragile. Pebble surfaces have little intrinsic strength so you'll need to lay a reinforced concrete paving base to offer sufficient strength to carry loads. Once the concrete is hard you can chalk your paper pattern into the concrete surface.
Lay the pebbles in small areas on a bed of mortar. You can select the colour of the mortar to enhance the effect. With white pebbles, a light mortar would be suitable – use a white, washed sand and off-white cement in a 3:1 mix. If you're using darker pebbles, or you want to off-set the colour of your pebbles, then use a darker sand and cement. Adding Bondcrete to your mortar mix will strengthen the bonding of the gravel.
The best approach to laying pebbles is to lay the outside edge first, then fill it with pebbles. Remember, the key to success is to place the pebbles as close together as possible. The pebbles provide the design, the mortar simply bonds them in place.