Being familiar with another ancient language such as Latin or Greek should help you to become familiar with the ways that Ancient languages differ from modern ones, but there aren't any languages which will help you to learn vocabulary in the same way that Latin helps with Romance Languages. Except perhaps Coptic.
My advice would be to have a look on the Internet first, and have a go at learning the core alphabet and trying out a few exercises. Then I would strongly advise that if you enjoy that you purchase a copy of "How to Read Egyptian Hieroglyphs: A Step-By-Step Guide to Teach Yourself"
(link). This is a great book for beginners, and instead of bogging you down in boring grammar it allows you to jump into some fun inscriptions and develop a few skills that will allow you to read cartouches, recognise certain inscriptions and so on.
Once you have completed that then I suggest that you try looking for a nearby club that teaches them, and purchase a copy of the only book that allows you to get to grips with the inner mechanics of the language- " Sir Alan Gardiner's Egyptian Grammar: Being an Introduction to the Study of Hieroglyphs"
(link). Amke no mistake. This is a tough book, but once you have a good knowledge foundation then this book will allow you to read virtually any Egyptian inscription that you come across.
I started Egyptian when I was 12 (around 2 years ago). I have finished the first book, and am getting stuck into the second one, which is a complete nightmare- but a fun nightmare. I am less than a fifth of the way through it; it's really heavy stuff. Don't be detered though, if you work at it then the reward far outweighs the effort.
Good Luck Isis!