I would say this, but I am also reminding myself as I say it. You should become more prudent as your capital increases. If you start from a small sum that you don't care about, you can do anything you want with it. But once you get up to five times as much, don't do what I did, and don't consider that money like meaningless. I blew it because after making money so easily I didn't treat it as precious. On the other hand, if I thought that money was so precious I never would have started trading, and never would risked any money at all.
Anyway, once you lose your whole capital a couple of times, and have to hold on to your regular job because of it, then you understand the correct balance between not caring about money (which I never did) and caring enough to use proper money management, something I ignored until now. Trading is a job, where, unlike most other jobs, the more you're driven to succeed and make money, the more you'll lose money, because of being impatient. That's why I developed a trading system - I was too impatient to wait for opportunities, and I cannot trade discretionary at all. I lose my balance within the first trade. But the unexpected thing is that now I still need to work on myself to let the system trade, and not interfere with it.
Also I would suggest that since you're gonna make a lot of mistakes at the start (technical ones, too - software, hardware), if you're starting with real money (I wanted action and didn't bother to do any paper trading), start really small, because chances are that you will lose. If you start with a lot of money you can't afford to lose it, and then you can't trade properly, can't practice, can't push your limits. From the year I started trading, in 1998, I lost my entire capital about 30 or 40 times, but it was always a small capital of sometimes less than 1000 dollars and (without considering capitalization and what it later became) 4000 dollars at the most. If I had started with 100,000 dollars, I would have lost it once, within a year, and never would have traded again in my life. Instead, by being poor and being forced to have a small capital, I tried everything, I lost everything there was to lose, learning lessons from it, and only wasted less than 40,000 dollars in ten years of trading, which is only 4000 dollars a year, and 300 dollars a month.
Finally, try to diversify as much as possible. By the end of this feat, I will have built about 30 different systems on 9 different securities. I think that is about enough. They all trade on different schedules and timeframes, that way I can use the same capital on all of them. So, even if they only made 100% return a year, I could sum up all returns together.
Having said this, I should just be quiet, because I talk a lot, but pretty much everyone on this forum is better than me, at programming, at trading, at making money. I just need to write things down to understand them better, so I keep writing and writing.