I've give you two tips for the price of one...
Always drill a small hole before using screws - this has saved a heap of frustration!
Wrap paintbrushes in plastic cling wrap between coats rather than washing in water.
Give yourself longer than you need. unforseen circumstances often appear that you did not plan for, so with any renovation project or small job, give yourself some contingency, so you can deal with the surprises!
Measure once. Cut twice. Nope. That doesn't sound right
Measure twice. Cut once. I've learned this the hard way. A few times.
Good one for this time of year - if you wrap your Christmas lights around a piece of cardboard when storing them, you'll never have trouble untangling them.
Use damp cotton gloves to clean venetian blinds.
Don't know if its the best tip ever but it's made life much easier for me!