Don't cut highs altogether, some highs will help your tone... experiment with an eq plug in and find good frequencies to boost and cut... lower mids from 250-900 are good to cut (not all of it, but one or two narrower cuts) boost some lows somewhere from 120 on down (shelving filter). Fret noise is good to cut, sometimes a de-esser will work for this, or just do a deep narrow cut and move it around until you find the noise (maybe around 4k to 6k, but it varies). A slight boost around 2k to 3k can add clarity and attack.

Use compression judiciously, too much will squeeze the life out of the track, but the right amount will really help.

For a synthier tone, try stompboxes (envelope filters, octavers, phasers, etc). Also try using an active bass as the tend to be more "full frequency range" in sound.

As far as copping the groove goes, you just gotta shed the stuff until you can make it feel good, don't settle for getting the notes right, it's all about precise rhythmic location, duration, and dynamics in addition to the right notes in the right order.

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