Same stuff you do with your right foot on the bass drum do it with the left. Also get a metronome and practice keeping a beat while doing quater notes on the hat and half notes and off beat stuff. Practice heel toe to and just get to where you can keep perfect time with your left foot without it messing up your playing.
I see a lot of people "tap" the hi-hat pedal on the 2 and 4 counts. Kinda makes an upbeat sound.. Playen on the upstroke. But uhh.... Yea! There really isn't a quick fix to getten good fast. It's all about diligence and hours of practice.
If you get stuck on somethin', just re-do it until it sounds good. That's one practice item I often use. Like if I fubar a fill ill just keep playen the beat and re-do the fill again and again until I get it.
Boy im off subject.... damn you Jameson whiskeys... Make me all smoggy in the brain.
Practice a bunch of different styles that require a hi-hat "chick." Swing and latin work perfectly. Do it on different beats. 1, 2, 3, 4, 1+3, 2+4, 1+2, 2+3, etc. Practice different times too. 5/4, 3/4, 6/8, 9/8, etc. Just find some patterns and start repeating. A good book to do some syncopation work, which helps overall independence is the book Syncopation. Check it out.