Decide the position of hard surfaces like paths, drives and patios before you do anything else because they will determine the level and position of many other garden features. Paths should be wide enough to walk on and must be kept free of wet leaves and moss, which can make them slippery and dangerous. In a small space, stepping stones are a good way to make a path. Space them sensibly for easy stepping: not too close and not so far apart that you have to jump.
You don't have to build a patio against the house, but this is often the most convenient place. Remember to look carefully at the level of the damp-proof course or position of any air bricks on your house. Paving slabs must finish no less than two courses of bricks below this level or you risk damp creeping into the house. If the back of your house faces north, it could be a bleak area to sit in but you may decide you prefer to have the shade in summer.
Have fun with the shape of paved areas: square and triangular areas can be more useful than long narrow strips. There are paving stones and bricks in a variety of colours to blend in with the style of your house and garden. Slates, cobbles and grit add colour and texture. You could choose 'natural' materials like wooden decking, or go for a modern approach with industrial steel and glass.
Whatever style of garden you have, it is worth adding some lighting. A clever garden lighting scheme will allow you to use your garden well into the night and make an interesting feature when viewed from indoors.
Once you have finalized your plan, you can start work. Transferring your ideas from paper to the actual ground can be tricky, so it's a good idea to set a 'datum line'. This is simply a line down the middle of your garden from which you can take all your measurements. You can mark it out using string and some pegs knocked into the ground, or you can use sand trickled from a bottle — but this will blow away in time. Curves can be marked out using canes and for circles, attach a length of string to a fixed post in the ground and use it like a big compass.