One of the best ways, in my experience, to rack up tons of happiness points is to be a writer. There are tons of wishes that provide between 1,000 and 5,000 points for writing books. In addition, those royalty payments really, really add up big, and that money can help you with lots of other achievements.
Combined with that, if you pick the "neurotic", "neat", and "loner" traits, you'll end up getting wishes like "make the bed" or "stay at home for a while" which add up really quickly.