You can win in online casinos and make money. Just don't wait to earn million of dollars. Play with your head and not with your mouse (don't click,click,click)
If the casino you play is reliable then you must experiment. We are talking about odds here so "invest" some money and test them

Fields of your experiment:
1. Various games
2. Different hours
3. Split your balance and play equal amounts every day. Not all your money in 5 minutes
4. Play with normal bets. Needless to say that with $0.50 or $1.00 you can still play but don't wait to win anything serious. My average suggested deposit is from $50-$500 (not bet, deposit) per time. My average suggested bet is from $1 - $20
5. In some games there are stats about the numbers (Roulette for example) use them
6. Some casinos give stats about the players. Go to less crowded games or try the crowded games with big bets (over $50 per bet)
7. Always check their alexa.com rank. If the casino is over 1,000,000 forget it. Choose only websites under the 200,000 rank spot ( in alexa the smaller number the better )

I saw online casinos that most of the tips above work (not all)


SOME BASIC RULES :
1. Don't expect to spent $5 and learn everything
2. Gamble is fun not a way to live. Online Casinos are Money Rearrangement not Money Machines. Face it Casinos are not a magical place that you will give you money from nowhere. Usually you WIN the MONEY someone else lost. However it's still Luck, use it with care.
3. If you loose, you lost. Calm down and visit the casino another time
4. Never, EVER, Gamble your Food or Rent or anything it's necessary for your life
5. Don't go with a new date to a real casino, or visit an online casino in an internet spot. He/She will probably abandon you