To answer your question and produce results, a pitching coach that understands the four major elemental influences in any breaking pitch which are: (1) torso projection (2) shoulder hinge, (3) elbow hinge, and finally (4) wrist and grip release, is your best bet.
Some pitching coaches will expand on these elemental influences, while others will abbreviate - meaning narrow down the list to only two or three.
In any event, the surface condition and how you feel personally on any given day also has an impact.
Now it would be so easy to say … proper mechanics this and proper mechanics that, but there are so many variables that kick in with the curve, slider, cutter, knuckle, knuckle-curve and so forth that your best bet is live time with a pitching coach. Also, since all of the aforementioned are consider to a greater or lesser degree breaking pitches, some of those mentioned are in the fastball family of pitches while others are not. I don’t mean to confuse you, but every breaking pitch does share some similarities with its cousins. So, if you have success with your slider, your cutter, or any other pitch with movement - bring that knowledge along when developing your curve. Experiment, try this-try, that- that.
In the mean time, at the top of this web page you’ll find an information bar that has PITCHING ARTICLES as one of the topics. “Click” on to that topic and scroll down to your come to pitching grips. There you’ll find a few articles on the curve.
If you plan on making it to the next level of this sport, try targeting your curve - or any other pitch for that matter, as a deliberate effort. Why? Because if you target your catcher’s left shoulder, for a right-handed batter, and you release, that curve will more than likely end up right smack dab going right into the sweet spot of the bat. OUCH! Any breaking pitch should be targeted to start at a point that allows the ball’s natural design coupled with your delivery motion to avoid the most damage by the batter. Again, a pitching coach can expand on this for your live time.