The first thing my mother always said was that you had to get your housework done before you could go junking. I have to admit I rarely do that. I tend to go when I'm stressed. Nothing like a good treasure hunt to lift the spirits and I usually see someone that has things worse than me so it makes me reevaluate things.
When I go in the door I always grab a cart if one is available. This is only because I almost always find more than I can hold. The first place I head is the furniture, lamps and housewear.
The only reason for this is I hate it when I see someone walk by with something I want.
At both Goodwill and Salvation Army, if you wish to buy a piece of furniture you tear the bottom part of the tag off and take it up to the check out. They usually give you 24 hours to pick it up. They will not come down on price and they will not hold it for you and you can not return it so make sure it is something you want. Camera phones are great for this. I have often taken a picture of an item and sent it to someone I thought might like it.
If it is upholstered furniture, make sure it doesn't smell. Stick your nose right down in it. If you are going to change the fabric it doesn't matter as much. Realize that even wood furniture can hold smoke smell.
If it is wood and you think you might be refinishing it, make sure it is solid wood. Veneer is alot harder to repair.
This is a cute little table I got at Goodwill for $10. This needed nothing except a good polish.
If you are looking at a couch or chair make sure the springs are still good. People have tried to fix this many different ways and I have yet to find one that really works.
Be careful of those tables that "just need a piece of glass". Glass cost alot more than you can imagine. That is probably the reason why someone gave it away.Great furniture finds are out there you just have to be patient.
Did you ever buying a used piece of furniture that ended up being a bigger project than you imagined?