First, if the sail obviously does better by moving things around, then do whatever the sail indicates it likes best.  IN GENERAL, however, you'd move the fairlead blocks AFT to reduce LUFFING.  But I think you are using the term luffing (the point at which the "belly" of the sail (max cambeer) just aft of the forward edge of the jib gets soft and pushed back in toward the boat, spoiling the airfoil shape, when you really mean flogging.  Flogging is when the AFT edge (leach) of the sail flaps or vibrates, so if you are experiencing flogging on th after edge of the sail, then moving the fairled block forward IS an appropriate solution.

 Ah, the mysteries of sail trim.  I've been sailing (and racing) over 50 years now, recieved coaching and attended various seminars and clinics.  Gone out in one-design (matched boats) where we varied trim to test what made a difference against the control boat. And with all that said I never feel like I've got it just right, and there's always somebody that seems to have things dialed in better on any given day.

I don't think anyone will ever be able to give you a good analysis without being there on the water with the boat.  Sail cut and wind speed might be the two biggest variables.  When sailing close hauled, here are some VERY general things that you'll find summmarize what you might garner from reading about trim and watching videios and from your local expert - and remember each effects the other and can EASILY be overdone, resulting if less velocity made good to windward (which isn't the same as speed through the water):

Your boat will point higher without luffing if the jib is flatter.  To flatten a sail you may increase luff (halyard) tension, move the fairlead aft, move the fairlead inboard, and increase the sheet tension.

You desire a flatter sail in higher winds, more camber in lower winds. A luffing jib certainly isn't fast, but a jib pulled so flat as to lose airfoil shape develops little power, and also isn't fast.

Bottom line is this: you want to "choose" an appropriate camber for your sails based on wind speed.  Then you want to achieve the correct camber shape for the sail along the whole height of the luff - so that most of the fore-edge (at least the lower 2/3rds) "breaks" into luffing at the same time.  Because you need more camber in lower winds, you'll find you must sail a slightly lower course to keep the sail from luffing.  In higher winds you'll have a flatter sail and will be able to point a bit higher.

Now, with all this said, and even though the set up of the jib will usually determine how you set the main when sailing close hauled, what you can achieve with sail shapes and sheeting angles for both the main and jib working as a team adds a whole 'nother layer of complexity.

Again, read some books, watch some videos, find a local expert, and most importantly spend some time out there on the water testing things out. Sailing fast (which really means getting the satisfaction of getting the most out of your boat, even if not racing against anyone) is a never ending search for perfection.

Bubblehead

Nicely said, Bubblehead.

Laszlo

 Thanks for that. Clearly I have a lot to learn!  

   Lil Ruthie:

Just remember not to stress, be safe and have fun while learning.  As "they" say: A bad day on the water beats a good day anywhere else. Not really always true if you've ever had a realy bad day on the water (sooner or later, everyone does) but anyway...

Sailing quotes are so much fun. Very applicable to this discussion are these: 

The goal is not to sail the boat, but rather to help the boat sail herself.

It is the set of the sails, not the direction of the wind that determines which way we will go.

“A sailor is an artist whose medium is the wind.” — Webb Chiles.

And then there is the classic:

“Believe me my young friend, there is nothing – absolutely nothing – half so much worth doing as simply messing about in boats.” So says Ratty to Mole in Kenneth Grahame's classic novel 'The Wind in the Willows'.