Mechanics, Consistency, Intensity

One of the most important rules in CrossFit is: Mechanics, Consistency, Intensity. Following this rule requires patience and dedication to fundamentals but will pay off in the long run with reduced risk of injury, better movement, and more PR's.
Your first order of business is to nail down the basic movement. If your air squat needs improvement, your overhead squat at 135# will probably be atrocious. Fix the mechanics of your basic squat (or other movements) and watch how much more easily you can do the complex ones.
Next is consistency. This could mean lots of SUCCESSFUL snatches at 80-90% before a new PR is attempted, rather than a 35# jump. Doing something right is way more important than doing it fast, so open your hips at the top of the squat, squat below parallel, get your chin over the bar, etc. Practice excellent movement ALWAYS.
LAST is intensity. Once you're able to perform movements very well you can begin to push a lot harder and move faster. Can't do 205# power cleans from the hang with solid mechanics? Use 185, 95 or 15 if you need to.
Don't be the guy in the photo above with an RX next to his name after the WOD, finishing 10 minutes after everyone else...

Strength:
Death by Strict Pull Up
One pull up 1st min
Two pull ups 2nd min
Three pull ups 3rd min...
Continue until you can no longer complete the number of pull ups in the minute. Sets do not have to be unbroken.

15-12-9 reps of:
135# Thruster
Toes to bar