[RWebb]

I've done almost all of mine - not cheap, but it isn't rocket science - you do want to use various products to "wrap" parts of the openings (butyl tape?) and pay attention to rain -- you can do a better job than some of the "pros:

milt and others know all the stuff and can walk you thru it

I am using 2 paned windows with an Argon fill & low e glass to meet the Energy Star spec (E*) and I get a subsidy (low interest loan help) from the local utility. I also have some trees planted in strategic spots & use low solar admittance glass (they have some other name for this in the trade but I forget it) in the high summer sun spots.

note there are two different approaches posted above - don't think you can buy either one this year or next