1. First decide what sort of impression you want to make with pictures. Do you want to be fashionable and arty or do you want to display family photos, nostalgia or personal interests? If you wish you can include all of the above, but you may make a better job of it if you have designated areas for each. For example you may want to make a statement with an impressive single abstract piece in your living room, while in the hall or dining room you could display more personal items. There are no rules as such, but try to harmonise your displays so that they do not compete for the viewers attention. If you can try and rationalise where and why you hang each item. Ultimately you will get more out of each piece and your guests will sense yours to be an organised and methodical household.
2. Keep your choice of art in proportion to where you will hang it. If a picture is too large it will look cramped and suffocated, if it is too small it will look lost and insignificant. Many people think that if there is room for a picture to squeeze in between the mantelpiece and the ceiling it will work there. Not so, you must allow the space around the picture to become part of the framing...