Firstly, find freerolls with a low number of players in the field and a high prize pool. Some of these might be password protected, or on poker sites
that you aren't on yet so look around for deals and select the best ones available to you.
Once you have selected some of the best freerolls that you know, you need to play as tight as you possibly can and take them seriously because most players won't be until you reach nearer the final table.
The way that you outplay everyone is by outlasting them so if you aim to last 3 hours and go in with a mentality of $0.01>$0.00 you will have beaten everyone trying to win first place in the first hand already.
The other thing you can do is get a calendar and track how many freerolls you played, and write down 3 hands you played well and 3 hands you played badly and your profits every day. If you go out with the best hand and the most equity, or if you cash on that day put a tick and highlight the day green, and if you get $0.00 and go out because of a bad play put an x and highlight it red.
You want to aim for more than 50% green days in a month. This will help make your subconscious more aware of what you need to do and will help your determination and bankroll management long term.
As long as you keep getting it in with the most equity you will win eventually. But the grind is long and you will get your best results when you least expect them due to variance. I have went days without cashing, then cashing insane amounts all at once, but I did not expect to win the full amount on the days that I did - I just intended to play the best I could again and again regardless.
So the important thing is that you just keep playing as many you can as tight as you can and you will get there eventually.
You can learn some strategy from freerolls that is similar to very low stakes MTTs and SNGs, particularly towards the end of freerolls. But be aware most staked games, especially cash games are completely different. Freerolls will generally only teach you how to beat complete fish and donks that care very little about the consequences of the risk - these types of players exist elsewhere in the game as well, but are a lot less frequent - unless one of your opponents is on tilt or a maniac.
That is why it is important for you to concentrate on your own game and try to play your best game at all times. Notice the player types you are playing against and as long as you're playing even a little bit tighter than their range then you have an edge.
As soon as you feel you are ahead in a hand, isolate your opponents and bet large for value. They will call if they have anything small so never bluff. I could type forever but I better stop now... good luck at the tables!