Ignore rare, difficult prefixes. But don't miss common and easy ones.
Here is just a demo to show how much you stand to gain if you pay a little attention.
Over-, above, beyond, too much, excessive
overact, overreach, overeat, oversleep, overcooked, overdone, overestimate.
overstep, overflow, overcharge
Under-, beneath, below, too little
undercover, underwear, undergo, underground,
underprice, undersell, undercharge, underestimate
Mis-, wrong, wrongly
misdeed, mislead, misjudge, misguide.
misunderstood, misinterpret, misfire,
misappropriate, misuse
misinform, misplace,
Un-, not
untrue, unkind, unholy, unhappy, unwise, unfinished, unfriendly, undone, unknown, unusual
unable, unequal, unimportant, unrest, uneventful
Un-, to reverse an action
uncover, untie, undo, unfold.