Theres no one area, the eve universe is huge!!
Khandid was good a while ago if you were an established producer/supplier due to the big bob war (9months ago), but a lot of traders jumped on it quick.
i used to hang around verge vendor/syndicate, piwating, YARR! When the new regions opened, GSKW-3 was a good spot if I remember right, you could make some nice money ratting with a raven and collectiong the ore dropped, no bounty, just pure ores which could be precessed and sold - that area is probably controlled now as that was several months ago.
a lot of the outer regions are restricted in someways to certain allinaces/corps. NBSI = Not Blue Shoot It, basically if your not in their alliance/corp then you'll show red to them and get shot down. you can make good money in empire, but its really hard work as you'll be competing with thousands of others for trading and producing. the real money is make outside of empire, but the comes with its own risks, mostly pirates and gankers/gate camps.
best thing i ever did was get into a low sec/0.0 corp, they usually have mining ops & mission running to raise funds for pvp action.
eves best played as a team, though once you have expeience solo can be fun too (insert Arazu with rails & covert ops cloak)
theres tones of guides to mining & trading in eve, google is your friend! So is your scanner and always keep an eye on Local when outside empire space!