This is a great quote and pretty much sums it up.

The hardest part of trading is realizing when you shouldn't be trading :p

Stocks are still much easier for me than daytrading simply because it forces me to wait 24 hours between the majority of decision making, as I don't feel like being a pattern day trader. Given those have some extrinsic value to believe in compared to just unreasonable expectations (as powerful as that is), there's something more to study, too.

Easily the biggest fund drain for most is the inordinate fees when making too many trades in too short a period. Often someone will end up changing positions so much they would have done better simply getting stopped out form the first one and taking a break.

Don't go all in and don't sell all. Perform steps and ensure that even if the price decides to sweep back the other way or further on, you can cut losses or capitalize as is reasonable.

You don't specifically need TA, but I find it to be a helpful source of "focus". Many people will overuse and rely on TA to the point they forget that TA is created and, as a result, fallible and not entirely reliable. It's a severe case of survivorship bias.