Tough to answer without hearing the track.
But, generally, to make them sound 'real', you want to program them 'real'.
Assuming you don't play drums, that might sound a little vague (hopefully drummers here understand what im trying to say
).
So I'll try to give a little insight from a drummers point of view.
IMO the most important thing I do to help my programmed drums sound as real as my real drum kit is to program a few different velocities/pitches of the same kit piece. Especially snare, bass drum, and hi hats.
'Real' drummers hit the drums and hi-hats with different amounts of power.
And I don't program ridiculous things that I (or any drummer for that matter) wouldn't be able to play (...well...unless im programming for 'drum and bass'
. But that's different.) But if it's in the context of a 'rock' song, I don't try to throw in some ridiculous patterns that not even Danny Carey could play.
And also, another tip to making things sound "real" is to have the quality of all the recorded parts match up.
Nothing gives away "fake" drums more than hearing a songs with amateur sounding recorded guitar/bass/vocal tracks mixed with a drum kit that sounds like it was tracked in Sound City. So you might actually have to bring down the quality of your drum tracks through a LoFi generator or something like that.
Now, I don't know anything about the garageband drums you're using. But yeah, quality samples/software do help.