Adjusting grain bill to gain efficiency...

I get my grains from my LHBS pre crushed but am hard pressed to get an efficiency above 65-68. I think my methods are sound so I am going to try to add some grains to offset the crush. My question is should I just increase all ingredients some fixed amount? If so what might that amount be so I could up my efficiency about 10%. Thanks so much!

I would just increase the base grain. I brew 6 gallon batches, and when I take a recipe from HBT that is for 5 - 5.5 gallons, that is the only grain that I will change. Don't forget that some specialty grains will not provide as fermentable sugars to the wort. Adding a pound of so of base grain should not affect the taste of the beer much - at least I doubt that I could tell.

Adding extra grains will increase your gravity, but not your efficiency.
Are you using some form of brewing software? If so, you should be able to set the efficiency to what you get, and the software will predict the OG for a given volume and grain bill.
If you want to increase your OG by 10%, then increasing the base malt by 10% should get you pretty close (assuming you are doing all grain).

-a.