Here is a mechanical method to select horses to follow...

List horses which last started at $1.60 (say 7/4on) win or lose anywhere!
Delete if 1) Win strike rate less than 25%
2) Less than 4 race starts
3) Older than 5 years.
Follow for three starts 1 unit, 2 units , 3 units stop at win.

You have a horse well supported at it's last run, good strike rate and with enough runs to have proved it's form.
The rules also limit your list of horses to ,I hope, the more likely future winners.

Example, Sheza Dragon last Tuesday Townsville 1st start won $2.40 Prev.start 2/1on. Of course some will be short but others reasonable.
For your improvement or dismissal. Good luck all.