When considering increasing efficiency there are several things to consider. Assuming the use of a fully modified malt one must take into consideration the crush and by that I mean exposing all of the starch within the grain while not destroying the integrity of the husk. That can be done by milling your grain with a millgap setting between .035 and .040.
As others have already indicated keeping the mash pH (5.2 is ideal) in check is vital. I use pH strips for checking the pH. The type of grain and water chemistry will have an impact on pH. There are some great books available that discuss this in great detail.
Mash tun and grain bed geometry will effect the run off. I use a rectangular cooler and typically acheive between 75 and 80% efficiency. Round coolers also work well.
Lautering. Get the sugar out...all of it. I use a Coleman Ultimate Extreme which has a recessed pocket below the tun floor which allows for all of the wort to drain from the tun. Some say the color is also important...red vs. blue but the jury's still out on that one.