Ignoring 2yr. olds [and 3yr. olds until Nov.].

Process of reduction method works OK.

I look at the total field and decide which horses will suit the distance, condt. and track and are having at least their 3rd. start from a spell, unless they are well know 1st or 2nd up performers or are trained by the likes of Hayes or Mick Price who turn their runners out fairly primed.
I then rule out any that are out of their class by checking the prize money average of each horse [a quick and dirty way to do it, but it's pretty accurate]. Also, if a horse's best effort was to win a $12k race and this is a $45k race, my money won't be on it.

Out goes any runner that won it's last start but has less than a 20% win SR.
Out goes any runner over 6yrs. unless it has a lot going for it.

Now I check out gear changes for the runners and any gear change they have with the possible exception of blinkers on or off first time, it's usually 'out' with them! Yes they might win, but the Pope might knock on my door too.

With the runners left I turn my attention to their last starts and read the steward reports of each runners last start and also check their last 12mths. history .....out goes any of them that has not won in the past 12mths. [it's surprising how many horses there are that haven't] as they are most probably never going to win again, regardless where they run.

Now I look at what type of runner each horse is, what barrier they have and who is going to be steering them. I do look to see if the runners can run time but it's not the be all and end all. Long as they can run suitable time for the class involved, it's all in the running.

Now I look at PP prices and if the couple of runners I'm down to are 1st. and 2nd. favorites, I forget the race. If they are not I'll work it down to a single bet. I do like to find back-markers drawn wide as they often have better odds than they deserve.

By the time I'm looking at what type of runner a horse is [above], it's all a bit of art, experience and luck, not science. Sometimes we paint a profitable canvas and at other times we don't :-)