I will get howled down by those that know better....but here goes anyway.

The 95 -98% that lose do so because they are lazy.
"I don't have the time", " I can't sit in front of a computer", blah blah blah, it's all too hard.
Most of that 95-98% would have fallen asleep halfway through the first post.
It may hold some good pointers but I switched off after a few lines.
At this point in particular...."Don't bet more than you (sic) afford to lose;"
If you go into this venture expecting to lose then I suggest you stop right now.

I write this as someone who today won on 20 of 27 races worked, and who has only had 1 losing day this month. Not bragging, just stating fact.

The first thing you need in this game is.....Discipline. If you don't have it, give up.
The second thing is a numerical ability. If you don't have, give up.
No amount of calculators or spreadsheets will help. By the time you've punched in the numbers, the price has gone.

It beats me how people go into this game thinking they will just win, without working at it. People who run successful businesses are then haphazard with their punting. It's like any other business. The harder you work the luckier you get.