To CD's point, I have a rather dead room, and I have cut three pieces of plywood about 1 meter square and I position these under the guitar and usually one behind and angled up to create some reflections. This helps give the recording some depth and color. CD didn't mention the obvious, but getting the guitar in tune is something to pay attention to also - and I echo what he said about new strings -- that can help with tone as well as intonation.