The basis for this article comes from the answer to the question, What's a good way to hang a picture on a wall? Selecting where, how, aligning it. etc.?, in the Answers Wikia.
Decide where to hang the picture. Avoid hanging one small picture on a huge expanse of wall - art looks better when it seems to extend the lines of furniture, windows or doorways or when several small pieces are grouped together.
Also consider the lighting. Direct sunlight can harm some materials. You probably don't want to put antique pictures or maps where they will be in the direct line of sunlight. Will lights glare on the pictures? Will there be enough light to show the pictures to good advantage?
When adding a set of pictures to a wall, you can cut out pieces of paper of the same size (like from grocery bags) and shape from paper and tape or pin them to the walls to figure out how you want to lay out the pictures -- where and how you want them to line up. Consider the height (usually eye level for someone standing), the closeness to other pictures or objects and the proportion of the wall space the picture will take.
- Check that you are not hanging a heavy picture on wallboard only. Hang heavy objects only from a wall stud or beam. Use a stud finder to identify places on the wall that can best support the weight of a picture.
- Hold the picture up and make a small pencil mark on the wall where the top edge of the frame will be.
- Choose an appropriate hook. You might want a two-piece nail-and-hook, or a hollow-wall anchor for heavier objects (see eHow to "Install Screws and Anchors in Walls").
- Holding the picture's wire taut, measure from the wire (or from the hanging tab if that's what the picture has) to the frame's top edge. Measure down that distance from the pencil mark you made on the wall and mark that spot - that's where the hook will go.
- Nail the picture hook into the wall where you've just made a mark.
- Hang the picture and adjust it so it's straight.
Use a handyman if you think you may have electrical wires where you need to put the fixing. Or if the picture is very big and you are not confident that the fixing you have are suitable.
- See http://www.ourhandyman.c.uk to find a handyman in the U.K.
Use a picture rail. With this technique you don't need to put any nails into the wall. The picture hangs from the rail. The height can be changed by adjusting the length of the wire and the horizontal placement can be changed by moving the hook along the rail.