Mmm... I know about not duplicating keywords in both tags and categories but didn't know about search engines not indexing titles. So it'd be a good idea to put keywords in either tags or categories (I'm concentrating on tags more) that are in the title as otherwise the search engine won't find it?
The other thing is, am I right in thinking that if I change the date on a post it gets a 404 error message in a search?
Here's the situation: my blog is currently not open to search engines but when I have finished all this work - and I shall be resposting some that were previously published, but just with different dates so that I don't lose any comments that they received - I'll be opening it to search engines. So - if it's the first time that the search engine has 'seen' the posts, would they still get 404's?
Sorry if this is confusing, I've been working on it for days and my mind is just boggled!