The gambling market is worth £14.5 bn in the UK with £5.6 bn of that coming from online sources. Globally, online gambling was worth $45.8 bn in 2017, and this is expected to grow to $94.4 by 2024. So it is safe to say that people love to gamble.
As they say, the house always wins, you should always gamble responsibly and within your means, you should be able to afford to lose what you put in, but that doesn’t mean you have to lose (a lot). Different casinos and different games all offer various odds, casinos will often offer sign up bonuses so you can, theoretically, game the system and make gambling profitable. Take BlackJack for example if you were to play the optimal strategy, the odds are always in favour of the house by around 0.5%. Famously, using card counting, the MIT BlackJack Team were able to game the system in their favour, and they not only managed to make money, but they earned a healthy $170/hour on average.
Card counting is not really a viable option with an online casino, but casino bonuses can be leveraged to make playing profitable.
Sites like Gamble Rock maintain lists of casinos and their relevant sign-up bonuses here: https://www.gamblerock.com/online-casinos/ – As there are some funny laws about online gambling in the USA this site also lists if USA players are allowed to play or not.
Using this, you can work your way through all the Casinos to make the most of your money. While Blackjack was the famous game to play in real life casinos to minimise your losses/maximise gains. For online casinos, slots have become a fan favourite. This is largely due to the low level of skill required to play the games, and they require little thought when playing, you can just grind through the game.
Different slot games have different odds, and games are often given a Return To Player (RTP) percentage rating and also a volatility classification. The RTP is the term that online casinos use to describe the percentage of all the wagered money a slot machine will pay back to the player over time. For example, if the RTP of a slot is 94%, you can expect to get £94 back for every £100 that you put in. The RTP is always calculated over the long term, so all variance (highs and lows) is evened out. If there is volatility that means you bank with vary by a large amount throughout a period of time, whereas low you will not have a big variation in your pot.
Typically a high RTP low volatility slot game will give you lots of small wins rather than a small number of big wins. This is perfect when you want to leverage casino bonuses as they nearly always require you to gamble to a certain amount before you can cash out bonus money.
While I would be reluctant to say that you can guarantee profits with online casinos and slots, using bonuses and playing the games with the best odds will at the very least minimise your losses, and should hopefully ensure you come out ahead.