Depending on the amount of capital at your disposal there brokers offer dfferent types of forex accounts so that you could start trading faster and be happy to get involved into the difficult but at the same time interesting world of online trading.
For those who have never had any trading experience the best way to gain some is to practice trading on a free demo forex account.
After you get the idea how the markets work you can invest some money of about a few hundred dollars into the micro- or mini-forex live account.
For more experienced and professional traders bigger accounts are more suitable. Brokers also provide better trading conditions on big accounts as they are making more many from big transaction.