First of all Trey welcome to IMHO the most interesting area of coin collecting.
Wildwinds is a good place for any beginners to start, lots of coins, info and pictures so you can see what is available, what it costs and decide what you like:
http://www.wildwinds.com/coins/They have specific pages for rulers and cities etc and probably the easiest way to land on the correct page quickly is simply to type what your looking for plus 'wildwinds' into Goggle and follow the link, 'constantine wildwinds' returns this link:
http://wildwinds.com/coins/ric/constantine/i.htmlDon't forget to hit the 'Browse with thumbnail images' option near the top of the page to see all the coins. Ctrl+F will also cut down searching larger pages if your OK on computers.
This is and excellent resource for IDing later (2nd and 3rd C) Roman coins (Where I would suggest you start collecting) and contains Helveticas tables, Excel spreadsheets that allow quick IDing of those coins.
http://www.romancoin.info/Lots of our US collectors like vcoins but I've not really used it and cant seem to post a working link atm
ebay is the best place to just cruise, hit the ancients section and see what you like the look of. No doubt in time you will find your own ancient niche, for whatever reason, and your collection and your knowledge will build up quicker than you think.
Later Romans are mainly common meaning decent coins can be picked up for cheap, this does not have to be an expensive hobby, for every $1000 coin there are 1000 $5 coins just as interesting to all but the most serious collectors.
Early Romans, Late Romans (4th C) and Greeks are generally more expensive, not prohibitively but when starting out I would keep your coins cheep and stick the the 2nd and 3rd Century, my opinion, others will be different.
Fake coins can be a problem but experience and trusted sellers are the best way to keep out of trouble, generally (but not always) cheaper coins are not faked much.
I buy almost exclusively on
ebay - its full of good sellers, but also has some not so good ones, its difficult to name good, cheap sellers as as they are trusted their traffic and prices rise.
In the US I've always liked this seller, though they dont seem to have much later Roman stuff on at the minute, also, stick to the auctions, not the 'Buy it nows':
[seller]taterthecat[/seller]
Honest stuff at decent prices and always been happy with their service.
Maybe these links will give you some ideas where to start:
http://www.constantinethegreatcoins.com/http://dougsmith.ancients.info/http://esty.ancients.info/