Well, I don't have a lot of time to expound... but even broad reaching (since the OP mentions this in the last parag.) you should still be able to get some use out of the tales. More importantly I have found that people tend not to ease the sails as much as they should. Actually on most points of sail this is true. So ease the sail out until it's obvious you're losing speed or stalling the sail. And maybe even more than going upwind it's important to keep in mind the effect your AWA has on your VMG. A very slight change in AWA could result in a significant change in VMG. Another case of where a handheld GPS is real handy. (project out a point that is directly downwind from your next mark but several miles beyond. Use that to see what your VMG is b/c if you use the mark you're steering for, your VMG is going to decrease the further left or right you get from a direct course.)
But that's another lesson for another day...
Just keep practicing. I used to take my Laser out on the local reservoir (pre 9/11) beat all the way to the far end and then sail back downwind jibing the WHOLE way to get better at jibing. I mean like 1.25 miles of this every 10-15 seconds!
Not that it did a whole lot of good.... lol