My ex fancied herself a day trader and spent an amazing amount of time researching trading, back-testing trading strategies, and coming up with new strategies. This was over around a decade. In the end, her "can't lose" strategy (high leveraged investment in a RITE with some sort of a "even if it fails we get our money back" option coverage) resulted in six figures just disappearing. I never got any sort of answer on what happened there, we were divorcing at the time and she wouldn't say anything about it. I'm pretty sure she didn't take it an run, she was just too embarrassed about it.
What has worked best for me is: - Invest early. When I was 19 I nearly took out a $10K loan to put into an investment account, just as a sort of "forced saving". I loved the toys, so that was a good way to make sure I got money into that. I wish I could go back and actually do that.
- Make sure you are taking advantage of your free money. I have a friend that isn't taking advantage of his work's 3% matching. I max out my Simple contributions.
- Putting money in a low-fees investment account. I have the bulk of it in a "targeted retirement account" at Vanguard, with the target retirement age set to around 70, which keeps it a bit more aggressive right now when I don't need the money and can contribute more.