Although there are many other ways of measuring a player's skills, his attributes are certainly the best and most obvious way in which to assess players in all positions. Finding out exactly what each attribute says about a player and which ones are most vital to each role on the field is essential and it's important to remember the following:
When looking at players attributes there are certain things to look out for in different positions:
For a Goalkeeper it's Handling (Han), reflexes (Ref), Positioning (Pos) and Command of Area (CMD)
For a Full back it's Tackling (Tac), Stamina (Sta) and Passing (Pas)
For a Central defender it's Tackling (Tac), Heading (Hea), Positioning (Pos), Jumping (Jum) and Composure (Cmp)
For a Defensive Midfielder it's Tackling (Tac), Stamina (Sta), Work Rate (Wrk), Team Work and Bravery
For a Winger/ Attacking Winger it's Pace (Pac), Crossing (Cro), Dribbling (Drl) and Acceleration
For an Attacking Midfielder it's Creativity (Cre), Decisions (Dec), Passing (Pas)
And for a Striker it's Finishing (Fin), Heading (Hea), Pace (Pac)

The Level which is deemed decent for each of these attributes will vary dependant upon the level your club is playing at, but a for a general rule at Premiership clubs you should look for players with 15+, at Division One 10+, and at Conference 7+.
In the lower leagues you'll have to accept that players won't be able to tick every box you require, and you'll have to determine which are more important for the tactics you're attempting to undertake.