First and foremost, it's important to work out the sunny spots in your garden. For the average garden, the main cast of shade is you and your neighbours' houses and outbuildings, but large trees can also be a significant source of shade.
The sun rises in the east and sets in the west travelling across the south sky. This means a plant that is north of a tall structure will be in shade throughout the day, a plant that is to the west in sunlight in the evening, a plant that is to east in sunlight in the morning and a plant that is south in sun throughout the day.
Not all structures cast the same shade. A birch produces dappled shade, which can be perfect for camellias and rhododendrons. A house will produce deep shade, suitable for only a few species.
Once you have worked out the sunny spots in your garden, you can plan out your garden. If you plan to grow fruit, you'll want to reserve the sunniest spots for such plants. Most fruiting plants prefer full sun (six hours of direct sun per day in midsummer) or cropping will be reduced otherwise. South-facing walls can be used to great effect to grow exotic plants such as grapes or train a fruit tree.
Ornamental plants will be fine in semi-shade (three to six hours of direct sunlight per day). Some species such as Japanese acers, rhododendrons, camellias are suited to dappled shade, and sometimes flounder in full sun. In deep shade (less than 2 hours per day), try planting evergreen trees such as holly, conifers and photinia. Flowering plants rarely do well here, but you can always try honeysuckle, winter jasmine and some varieties of rose and clematis.