I made a basic desk out of common lumber.
For the drawers, I didn't use ball-bearing slides in order to save money. So they are just wood sliding on wood. It's ok, but I'd like the action to be smoother.
What can I use to lubricate the wood-on-wood mechanism? I vaguely heard that wax might be an option but am open to hearing of a better product.
Ideally, it'd be cheap, easy to apply, and be long-lasting.
finishing - What can I coat a wooden drawer slide with to reduce drag? - Woodworking Stack Exchange
Helping wood to slide well - Canadian Woodworking and Home Improvement Forum
How to lubricate wood drawer slides? Wax?
What’s the best way to lubricate old drawers that only have wood to wood contacts?
Videos
A good go-to solution is wax. Either some paste wax, or in a pinch you could rub a candle on it.
I've also rubbed a bar of soap on wooden drawer slides in the past, though I'm sure there are plenty of reasons not to use soap.
candle wax as mentioned in the other answer.
Otherwise glue some hardwood strips on the surface. Hardwood doesn't wear as fast as softer woods and be able to provide a smoother surface.
There are some low-friction tapes you can stick to one or both of the surfaces.