2) To precisely apply joint compound, mortar, or plaster filler to cracks or joints, use a quart sized Ziplock bag like a pastry bag. Fill with your compound, twist the top, soften by rolling between your palms, then snip off a tiny corner and apply.
4) Remove a stripped screw find a screwdriver with a tip that matches the screw type. Tap the tip into the head to 'set' it. Then applying as much force as you can onto the screw, slowly back it out.
5) To remove a sink clog or retrieve something that slipped down the drain (especially tubs ans showers which are hard to reach) use a wet-dry shop vac. Place some nylon pantyhose over the vac hose - if you're trying to suck out jewelry - and create a seal between the drain and the vac hose - electrical tape works well. Turn on the vac and the clog/item may come free. 
6) Loosen a stuck nut with a socket wrench instead of pliers and wrenches that can slip. First try to tighten to see if it moves. Next tap the side with a nail set to loosen rust or paint. Try a hairdryer to expand the metal. Last, try Liquid Wrench several times.7) Prevent stuck bulbs in outdoor fixtures - the bases can corrode - by rubbing a bit of Vaseline on the threads before you screw them in.
8) Safely hang heavy items without worrying about missing studs by creating a cleat for the wall and the item to hang. Run a strip of 3/4" plywood (twice the length of what you want to hang) through a table saw with the blade at 45 degrees, creating a beveled lip on one edge. Cut the strip in two and place one strip with the lip facing up, on the wall. Check for level first. Secure the other strip to your item with the lip hanging down. Lift the item into place so the two lips meet and interlock. Paint the ends of the strip to match your wall.
10) Make straight cuts with a handsaw by looking into the blade! Rest the saw teeth on the edge of your cut line and when the reflection matches the actual edge of the wood, saw away.