No matter how good your system is, having some idea on whether you're going to be on the right or wrong side before opening a position is something that is a bit easier said than done but by no means impossible.
I would say that the more decimals / prices there are to trade in, the more likely you're going to be on the wrong side. If the only prices available were 1 and 2, and nothing in between, surely buying at 1 and selling at 2 would be easy. Once you bought at 1, the middlemen would add decimal pricing, and price would move to eg. 0.9, for now. Then when someone sold at 0.9, they'd add more decimals, price would move to 0.95, Now someone buy 0.95 and price move to 0.925 etc. All speculators will lose. Scaling-in / out complicates this scam, so that's why you have margin, so that you can't scale-in or out as the leverage wipes you out first. Deposits mysteriously get lost for a while, until you get closed at bad price and then the deposit goes through. True story.
The 4th page below goes into why I've recommended to get your credit from elsewhere than brokers if you must use leverage. (another reason is, the bucket shops don't really need to even manipulate prices to blow up traders... the other traders will do it for them - but if they don't and you get to hold profits overnight, then more complex gears kick into action that make sure the max money is lost. Either the broker manipulates prices, gets someone to do it or just wait for option market makers to do it prior to expiry - this whole scam is automated with "optimal market making" algos, which is why few companies make millions a day, no losing days)
I would say that the more decimals / prices there are to trade in, the more likely you're going to be on the wrong side. If the only prices available were 1 and 2, and nothing in between, surely buying at 1 and selling at 2 would be easy. Once you bought at 1, the middlemen would add decimal pricing, and price would move to eg. 0.9, for now. Then when someone sold at 0.9, they'd add more decimals, price would move to 0.95, Now someone buy 0.95 and price move to 0.925 etc. All speculators will lose. Scaling-in / out complicates this scam, so that's why you have margin, so that you can't scale-in or out as the leverage wipes you out first. Deposits mysteriously get lost for a while, until you get closed at bad price and then the deposit goes through. True story.
The 4th page below goes into why I've recommended to get your credit from elsewhere than brokers if you must use leverage. (another reason is, the bucket shops don't really need to even manipulate prices to blow up traders... the other traders will do it for them - but if they don't and you get to hold profits overnight, then more complex gears kick into action that make sure the max money is lost. Either the broker manipulates prices, gets someone to do it or just wait for option market makers to do it prior to expiry - this whole scam is automated with "optimal market making" algos, which is why few companies make millions a day, no losing days)