If you're interested in an exchange you should consider one where a lot of trading volume is being done. For margin trading okcoin.cn and bitfinex.com are good. Okcoin.com is still developing. What's good about these sites is that you can implement 3x leverage. Leverage is a useful tool for augmenting your trading balance.
And then there are the okcoin.com futures that lets you use up to 20x leverage. It's slightly different from margin trading so it takes a bit to learn but futures are also another good tool for trading.
Profitability is slightly dependant on skill. Everyone might have a slight edge in different areas, or you can just suck at trading. Trading takes experience and screen time. Don't think of it as easy money.
One of the main goals of trading is to not lose your money. If you don't lose all your money you'll be able to come back to trade another day.
Another key to trading is patience. You need to wait for good trade setups. If you overtrade then that can lead to disaster. You do not always need to be in a position. Wait for high probability trade setups.
I trade purely on okcoin.com but another site might be better in your situation. Okcoin futures offer up to 20x leverage and offers 0.03% trading fees.
https://www.okcoin.com/?invid=2033157Also note that you can both long and short which means you can profit off of any direction. If you're new wait for good entry points for longer term trades. Other people are better at scalping which is short term trades for smaller spreads.
And I think the other thing about the bots is a bit ridiculous. Bots can help add liquidity to the market. They also just implement strategies, and those strategies can be wrong.