Hello and welcome to CoinPeople.
I'm sure lots of folks will be along to give you the standard warnings that purchasing coins is NOT an investment but a hobby and one must be very very careful. OK That said, since you're new and considering purchases for investment as well has hobby you need to decide on a few things.
1) Length of investment ---
2) Personal desires -- do you have particular series, etc that you prefer. What about gold, silver, commems, etc.
3) If you are considering moderns I'd suggest you consider only certified coins until you get very comfortable with grading and telling fakes, etc. on your own. Pick one of the majors PCGS or NGC and stick with them for all your purchases. Join their boards - use the free membership until you decide what you're really into. Post and read. Get some books -- purchase, library, borrow from friends and read read read. Hit some shows - don't buy - observe.
4) Think about a local coin club and maybe the ANA.
Above all -- have a great time.