I'm not one of the huge earners. I've only been matched better for 5 months but I've amazingly hit £2k for this month which I'm chuffed to bits with.
Casino offers can be no risk so free spins, of money back on all losses or a free bonus. Or low risk so wager £5 for 10 free spins or wager £10 for £5 bonus. You decide on an amount you are happy to risk. My personal amount is £50. You only do offers that are positive expected value. So if an offer is wager £10 for 10 free spins on a slot with an rtp (return to player) percentage of 96.5, you would expect to walk away with £96.50 if you wagered £100 on that slot. The variance affects it so low varies is over £100 and high variance is close to £1000+. So the value is in the bonus or free spins. That what brings the expected value into profit. There are calculators for working out if an offer is positive expected value.
Low risk means they have no wagering requirements or a small amount, say under 5x. So you would have to wager your winnings from the free spins 5x before it was cash. And are for a small amount of money. £5-£20.
You can't lay casino bets. You can lose your entire £10 four times in a row. And then the next offer you win £44. The EV always plays out, but you have to have the bankroll and the stomach to not take losses as loss.
There are plenty of no risk offers out there. William Hill have free spins most weeks. Betfair arcade, bwin, grovesnor, skyvegas do free spins and also money back on all losses on roulette up to £10. So you do 10x £1 spins on roulette on one number. If it wins, you win £36, if you lose all 10 spins, they refund you £10.
Roulette isn't great for wagering as red and black is less than 50% chance and I have seen 18 blacks in one go.
£800 Profit is amazing. I am trying to expand into each way and extra places on horses as I dont think my record month is going to be doable next month with less casino offers around.
A good rule for casino offers is either chose a percentage of your bank roll as you maximum riskable stake. 10% is a good starting place. Or a percentage of your month profit. So 10% of your £800 Profit and day 'I will only do £80 worth of low risk casino offers in April' and carry on doing it like that.