A long time ago (decades, probably) there was a vogue amongst gamblers for being dismissive of 'systems' and then saying that what they did was to use 'methods' for selection. In the end I suppose you pay your money and make your choice, but the difference between the teeth of that fine comb of definition escaped me then, and still does. Each gambler has their own likes and dislikes - and their taboos. My personal taboo is never to back each way - it only takes a moment to calculate that the 1/5 offered on a 33/1 shot that finishes 2nd or 3rd is not 6.6/1, but 3.3/1 - and you are still trying to find a 33/1 shot to place.
One of the 'methods' that was popular for a while at least used current form as a basis - look for horses that put up improved speed figures in a better race LTO - 'better' was defined by value of race e.g improved figure in 30k race LTO, now running in 20k race. It was a starting point, and was useful. It had some success then, and is probably a good yardstick still. At the time it was known as the Van Der Wheil method - apparently named after a gambler.