I think league tables are a useful starting block, especially if you look at them for a few years, Look at the value added bit as well. Many teachers think that counts for more.
speaking from experience of sending my sons to three different primary schools, mostly due to house moves, I'd say:
check the head is a good one - difficult to do as a parent, but see if you can find out some facts. Heads' reputations travel fast IMO. Has he/she a good strong leadership style? does the head support the teachers (IMO really important) I'd have reservations about choosing a school with no proper head, unless the current head was retiring.
Also, I think it's a good idea to see what happens at school pick up time as others have said. And see what the staff turnover is - are there lots of supply staff? IMO it's better if my sons are taught by the same group of teachers as much as possible.
As a very general rule of thumb, I'd pick a smaller school over a bigger school if all else fails. At least the teachers are more likely to know all the pupils by name. My son felt the two big primaries he attended were a bit impersonal - he much prefers the feel of his very small primary.
I think another thing you can do definitely, is to chat to local playgroup leaders, local nurseries, cub and brownie pack leaders, anyone really who comes into contact with primary aged children in the area you want to move to, and ask them what primary schools they would recommend. Word of mouth from people who know the current state of the schools is invaluable - but still not necessarily the whole truth - but it's a good start! HTH