The striker has re-signed for the club after leaving Wealdstone.
The forward scored 12 times for the Stones last season as they reached the National League South play-offs.
Pratt is back where he is loved and the manager thinks he will make up for lost time after leaving back in December 2017.
Collier is looking to improve his squad and push on in their third season in the league and he feels the recapture of the forward will help that.
He told the club’s website: “David was top of our priority list when we discussed recruitment.
“He finished as Wealdstone's top goal scorer last season and will add undoubted firepower to our offensive options.
“His work rate and desire ensures his signature will prove very popular with the fans.”