Day trading has always been a tough game, requiring a very strong psyche, discipline and a high level of trading skills to succeed in.
Nowadays though it's even harder due to the stronger competition, not only by humans but especially by computers trading at a speed a human trader simply can not match up to. High-Frequency Trading is happening in literally all of the popular markets out there and like Chess, scalping has become a game where humans cannot win against the AIs anymore. Add to that the speed/location advantage of the HFT shops and the odds of success decrease even more.
My advice is to forget about scalping. Even without the trading bots, odds of success to make money scalping are very low as the trading costs involved are incredibly hard to overcome. To not get completely killed by trading costs you need to trade in very liquid markets. But that's exactly where the robots are.
But not everything is lost, maybe all you have to do is to slightly adapt as a day trader. Here are some of the things you can do:
The longer your trades last, the higher your profits (and losses) will be on average. It's a simple fact, if your trades last 4 hours on average, you'll be much more likely to catch a big move than if you average trade lasts 5 minutes. This way the HFTs can't hurt you as much anymore and also trading costs will have much less of an impact.
You don't have to do 20 trades per day to be a successful day trader, quite the opposite! The more you trade, the higher your trading costs and believe me these trading costs will kill you in the long run.
Don't get married to a specific market, instead, diversify your day trading over different, uncorrelated markets. This will strongly increase your chances of success as you'll stop seeing opportunities in a market where there aren't any.
Day trade only markets that provide a good bang for the buck. I do this by looking at the average daily range of a market in relation to the average trading costs.
Trade the news. I know you often hear the opposite advice but if you learn how to do this right, trading the news is one of the best ways to day trade. Just look at the markets, especially currencies. Isn't it true that most big moves happen right when some economic report is coming out? Sure, volatility explodes and liquidity often isn't that great. But hey, isn't high volatility exactly what you're looking for as a day trader? Now first you need to do your homework of course and have a plan ready on how to trade each of the specific news events.