Hi...it all depends on your level of tactics skill. The highest recommendation I can give is for the
Seirawan and Silman "Winning Chess Tactics." It's a good, basic book, but Seirawan is an expert
not only at chess but at teaching and he explains things much better than the average author.
The nice thing about it, is that you go through it and are tested over the tactics you've learned at
the end of every chapter. At the end of the book, Seirawan presents you with three sets of tactical
problems, easy, medium, and hard. You have to solve them and score at a certain level for Yasser
to say that you're ready to go on. After that, you should look into the Polgar book on chess. It's
mammoth, but you'll never be for want of a chess problem. Go through the first 450 problems over
and over until you can do them with relative ease. After that, more advanced study is required and
you should get better recommendations. There's a good article on studying tactics on www.chessville.com.
Hope this helps!
p.s. The 1001 problems are public domain and can also be downloaded from chessville.com.