I recommended starting out with either EoSD or PCB, then moving on to MoF or SA, then finally IN if you still want more.
EoSD and PCB are great to start beginners off, and this way you can really appreciate the more refinements made to the later games. IN is mostly micro-memorization bullshit, so I would stay away from that game entirely, probably just keeping it archived in your computer somewhere.
In addition to whatever game(s) you choose to start with, I HIGHLY recommend getting Shoot the Bullet. This is important. As a beginner, one of the fastest ways to improve is by StB, as it gives you direct spellcard practice, which is the essence of the game, not to mention the hardest part. Stages don't give much practice.
You're welcome.