020: Don't fear the ADR.
Of all the lessons I learned working on Hide and Creep, "Don't be afraid of ADR," might be the most important.
"ADR" is short for "automated dialogue replacement" or "additional dialogue recording." I prefer the latter definition, as there is nothing "automated" about ADR in the low-budget world.
I spent many hours trying to fix Hide and Creep problem audio -- dialogue recorded on set marred by traffic noise, airplane noise, and/or poor choice of microphone placement. It would have been easier (and, in the end, better-sounding) to just rerecord any problem dialogue.
There is one cardinal rule of do-it-yourself ADR: record the sound as "dry" as possible, with no natural reverb. Have the actor get close to the microphone and record the sound in a small room with carpeted or padded walls. The reason for the dry approach is simple -- you can easily add reverb to dialogue in post-production, to make it match the sound of the original room, but you cannot remove reverb.
I've been working on a new setup for Interplanetary ADR. I'll post details after I've had the opportunity to try it out with an actor (hopefully sometime next week).
EDIT: Looks like I opened up a can of worms with this topic. Please read the comments for more ADR info.