I think that it is good to sometimes make a "less than optimal" enchant from time to time. Sure, another option may be better in a general sense, but tossing in a Decoy every now and again has done me some good, as has putting a Nullify on a large Creature early on, well before it is needed. (I usually save Nullifies for my Mage.) One time the Nullify on the Creature idea saved a push through a wall of thorns after my opponent corroded its armor.
Also, when you play against the same two or three people all of the time, it can be good to change up your openings, enchantment play, and overall level of aggressiveness to keep from being completely predictable.