here are two metods for example
let's say i'm buying a striker

- filter out all strikers, x4/x9 quality, let's say 18yrs old
- check their value, let's say all of them have similar value ~20m
- come back later, same filters, again all of them cost ~20m
- come back later, same filters, one of them cost 32m, i buy him, or i try at least

another method i use is at day 1 of the new season, when you play two cup games
- filter out all strikers, 5 stars, no age or quality restrictions
- click on them one by one and check their statistic from last season
- one of them is 26, quality only 71(i can buy up to 74) but he scored 76 goals in 72 games
- i buy him, or i try at least