i was in your boat (until just recently) for a while, too. i was getting efficiencies in the 60s and occasionally the low 70s. here are some improvements that i credit my new found efficiency (90%
1. BierMuncher's Hybrid Sparge technique
-extremely easy to follow through with and works like a charm. i use a simple soup ladle
-i recently started stirring my mash a lot more. i'll heat my strike water usually 1-2 degrees hotter than it should be in order that i'll be able to stir for 5 or so minutes without going below my desired mash temperature.
-i'll also stir again 30 minutes into the mash. usually at this point, starch conversion is mostly over, so temperature isn't as important.
-i'll mash out at the end of my 60 minute mash and stir vigorously before sparging.
3. Grain Crushing
-i know there's a lot of opinions on the effects that grain crushing has on efficiency, but i am fully convinced that a finer crush significantly increases one's efficiency. my last batch i tightened my rollers up to achieve a finer crush. this allowed me to get my efficiency at 90%. i'm not sure if you own your own grain mill or not, but if you don't, request that your LHBS crushes your grain finer. this helped me a lot! also, make sure to put some rice hulls (these will add 0 sugars/flavors/aromas) to your mash in order to prevent a stuck sparge.
again, these were the three biggest advances in my mashing/sparging process that raised me up to a 90% efficiency.