Nandina domestica

Determine soil type

Select the right plant for the right place considering the soil type.
Dry soil - If your garden is overshadowed by trees, conifers, hedges and shrubs or in the shadow of a building, the  soil is likely to be very dry. Adding plenty of organic matter prior to planting will help moisture retention.
Moist/Wet Soil - Often shady sites have damp soil which can become waterlogged in the winter months. The best way to tackle this kind of soil is to incorporate plenty of compost and horticultural grit.
Good Fertile Soil - If you have a good dark loamy soil which is free draining but not dry then most of the plants in the range will establish well.

Viola od. 'Queen Charlotte'

Plant combinations

Combine plants with differing colour, texture, structure and seasonality for the best display.
Colour - can be provided by foliage and flowers but also by colourful stems of shrubs like the Dogwood aka Cornus.
Brighten up dark spots with colourful evergreen foliage plants e.g. Heuchera & Bergenia
Texture - Combine lush foliage plants and bold perennials with more delicate plants to add interest.
Structure - Plant shrubs for structure and then interplant with more delicate perennials. 
Density - Plant in groups of 3,5 or 7 of the same plant rather than individually.  This will have more of a visual impact and appeal than a tapestry of individuals.

Acer dissectum

All year interest

Seasonality - Choose plants that will flower at different times of year.  That way you will have interest throughout the seasons rather than just a splash in spring or summer.  Shrubs like Viburnum 'Eve Price' flower during the winter.
Look for plants with attractive berries, bark, stems & structure to extend the seasons.
Ground cover - Select low growing evergreen ground covering plants to suppress weeds & lock in moisture. See our list here.  These can be interplanted with bulbs to extend the season of colour.  Look out for Muscari, Cyclamen and Arum.