Hey there, I would suggest starting out with a monitor species that will be fairly easy to learn about and stay relatively small. Look into ackies (varanus acanthurus) they normally get close to 2 feet in length, also they are all captive bred here in the US, not imported as most larger monitors. I started out with a group of red ackies and have learned quite a bit about monitors from raising them up. (Still have a lot to learn though...)
You would really enjoy ackies. I know I have, mine are quite active and have many funny/interesting behaviors. They will also give you a good idea about their feeding requirements...as it will be multiplied many times with larger species. There is also a considerable amount of information to be found about ackies, so just do your research. Proexotics' site is a good place to start your research. Definately consider the smaller species, they are very enjoyable to keep. Hopefully others can add to my response with other possible suggestions. Cheers, Lance