Hi Dave, I assume the sail in the picture is your headsail?  Fancy!  Looks expensive.  I couldn't see any telltales on it, maybe they're just not showing up in the picture, but they prove helpful when positioning the jib car.  As a general rule of thumb, to point upwind the highest, you want the least camber in the sail, so flattening the sail out and moving the car AFT is usually best.  Downwind, in light air, you would want the car FWD.  Other rules of thumb include positioning the car so that the line drawn from the car, along the sheet to the clew bisects the clew and projects into the middle of the luff.  In racing, these guys spend a ton of time tweaking every last tweakable thing.... halyard, sheet, car, vang, cunningham (who?!), back stay, etc, to eek out another 10th of a knot.  These guys are incredible and have my respect.  I'm just a cruiser and when I get the boat going 6+ knots I tend to be happy.  But I use the TLAR method and position my cars fwd going downwind and back going upwind.  That seems to produce a decent sail shape.  But again, a true racing enthusiast will have lots more detail in to the physics behind all this.  

Mike

Mike, please re word following statement:
Other rules of thumb include positioning the car so that the line drawn from the car, along the sheet to the clew bisects the clew and projects into the middle of the luff.
Sorry man, no comprendo...
Thanks. 

Congratulations on your successful race, and I have to add “nice looking sail”.   I actively raced for many years and enjoyed it a great deal.   

The old school method for adjusting the jib lead position it to sheet in and slowly luff into the wind.   The entire luff of the sail should start to feather at the same time.      If the top of the sail luffs first the jib lead needs to move foreword.   If the bottom luffs first the jib lead needs to move aft.  

This is also evident by the tell-tails.   All the inside tell-tails should lift at the same time, top to bottom.   

Moving the fairlead further outboard while reaching makes sense, opening the slot.   Adjust the fore/aft position based on the tell-tails, they should all lift at approximately the same time.   

The attached article from sailing magazine explains it better than I can.   The North sails article is good too.   Remember every adjustment impacts every adjustment.

Have fun,

Ray

http://sailingmagazine.net/article-17-sail-trim-101.html

https://www.northsails.com/sailing/de/resources/enterprise-tuning-guide