Great topic to start as it's an issue that's not discussed anywhere near enough between people who like a bet. The basics for me are:
Have a bank and have a points system around your bank - none of my bets are bigger than 5% of my betting bank, if I go up to 5% then I'm seriously confident of my bet.
Have a spreadsheet of all your bets which shows your profit/loss - Best thing I ever did.
Have a specialist area that you bet on - for me it's Class 2 or above chases and handicaps on the All Weather between 5f-1m. Immerse yourself in the areas, knowledge is king.
Price up anything you wish to bet on yourself without looking at bookmakers prices or forecasted prices - only way to determine whether your selection holds value.
Finally, if the price is wrong DON'T PLACE THE BET. Biggest error punters make is trying to find the winner of the race. Anyone can find winners, finding value is the difficult part. If you're backing 2/1 winners relatively consistently but they should have been an average of 4/1 you won't make a profit long term. Beating SP is a must so finding your own edge is imperative.
Above all else discipline is key. Stick to your beliefs even during a losing run and you won't go far wrong.
As you say though these days the trend is picking a big accumulator and dreaming of winning big. I'm happy backing in a 0-60 handicap at Dundalk on a Friday night knowing I'll win long term