hi thar, welcome to HeRO!
customs info etc are in the forums and wiki.
to get you acquainted with RO, you might wanna check out the following sites:
http://www.irowiki.org
http://www.ratemyserver.net
google "RO data zone"
google "doddler's RO"
google "roratorio's calculator"
basics are simple, make a merchant and get 10 Overcharge and 10 Discount. Keep it under level 40 to let it get unlimited free resets. If you need to buy supplies, use the merchant. Same goes for when you are trying to sell items to the npc for some zeny(cash/money/moolah).
the best(relatively cheap and fast) starting out classes would probably be aco-priest and archer-hunter. You might also try going merchant-Blacksmith with an agi build because they're quite cheap too, same goes for agi swordie-knight. If you like agi build then don't forget to gather some money and get a cheap pantie-undershirt combo for around 30k from players.
HeRO also has a custom system in place which may help newbies, so if you get a card, check the wiki hatter page and you can sell those hatter cards for 300-400k. Really helps for you to start up... hell i was bamboozled to selling my spore card for 200k when hatters was 500k when i first started out, but 200k still did help quite a bit... oh and although it may sound enticing at first, but i would recommend you buy fish from players rather than pots from npcs because fish is somewhat cheaper and better for pvm
GL and HF!
-w-