Quantizing MIDI notes to precise rhythmic values on a grid can sound "mechanical." This isn't necessarily a bad thing, particularly with techno, electro, etc. But for musical genres that aren't quite as rigid in terms of tempo, overly tight quantization can sound stiff. Enter groove quantization: instead of quantizing to a grid, you can call up a particular groove—for example, a hi-hat riff played by a real drummer, or a hand-percussion part—and quantize to that instead, forcing the MIDI notes to conform to the beats in the groove.
Different programs handle this differently; some come with a bunch of preset grooves (like shuffles, humanized percussion grooves, swing, and grooves that lag or lead the beat), others let you extract grooves from existing audio or MIDI clips, and still others combine both options. In fact, this might be time for a bonus tip—sequencers come with documentation. It may be an intimidating amount of info, but read a little bit at a time, and you might find some real nuggets of useful information.