best book on chess theory

Hi, I'm interested in improving my game (like everyone I guess).   Can someone recommend a good book on theory for a 1250 rated player?  I'd like to focus on developmental tactics and strategy.  Ideally something not too advanced, but more interesting than just the basics. 

Thanks

I recommend Seïrawan's winning chess openings

Thanks for the reply, i'll check it out

hicetnunc you look a bit like kramnik :)

i like chess fundamentals by capablanca. i also like "the giants of strategy" so far

the middlegame of chess by reuben fine (revised by hochberg) or any other middlegame books.. when i was 1200 i read that and now i got 1400.. not that it makes me a strong player but at least i got better than my playing strength before..