While everyone has made great comments, here is what I would suggest.
1) Get a book -- either the ARRL Technicians Study Manual, or the Gordon West book. Books are handy and at least with the ARRL Book, it is a handy reference for later (I still sometimes use mine).
2) On line study -- there are some great web sites out there, some are fee based, others are free. Another great thing is the availably of online practice testing. You can take as many practice tests as you want.
3) If possible -- take a class. While they may not always be available in your location, classes do help. I speak of this from experience. If you are not really self-motivated, or have problems this is the best way to go if you can.
About [10] years ago I wanted to try and start to get into Amateur Radio. I had gone to our local Field Day, and was told to get the book (the above mentioned ARRL Tech Study Manual also known at that time Now Your Talking, from Radio Shack), study it and come and take the test. Well, starting cold, and not knowing anything after awhile I got bored and after a few weeks (or a month or so) I gave up. It was not until I found out about classes did I go for it again. I managed to dig out my old book and took it, finding out it had everything I needed so I did not have to take notes (and since I cannot write anyway...). However, for my upgrades, I was able to do mostly self study.