The most effective thing I can think of, is if you ever see a clutch (or whatever the collective noun is) of spider eggs in the house, don't ignore it, get rid of it. We used to be fairly relaxed about seeing spiders in the house, but found that you just end up with cobwebs and spider eggs all over the place. Make a point of throwing each spider you see outside (I expect they'd die of starvation/dehydration in the house anyway, so you're probably doing them a favour), and get rid of any eggs you see.