Drywall holes can be repaired one of two ways depending on the size
of the hole.  If the hole is around four or so inches and smaller, you can
plug it and fill with durabond.
To plug a smaller hole in drywall, you can use a paint stir stick or
something similar about two inches longer than the hole.  Screw in a
drywall screw in the center so that you can hold the screw and slide
the wood into the hole and pull tight against the back of the drywall.  
Then screw through the drywall into the stick on each side of the hole,
sometimes it helps to drill a small hole so that the wood doesn't split.  
After the wood strip is secure, screw the center screw that you used to
hold the wood against the drywall in just under flush with the face of
the drywall.  Now your ready for drywall compound, or as we call it,
"mudding!".  Always use fairly thin layers of mud, building up the
layers until the surface is just above flush with the surrounding drywall.
The most important part of prepping drywall and trim is to use professional products.  Large
home improvement stores will sell you patching compounds that are premixed and difficult to
sand, durabond easy sand powder is the only way to go and sands very easily.
Caulk that's 45 year warranty or more, with elastomer's and is paintable will give you the best
results.  Mesh drywall tape holds drywall compound better than the old drywall tape, make sure
it's mesh!  A hammer will be needed to make concave areas where there is any raised drywall.
And a 6" flexible mudding knife to spread the drywall patching compound. (also known as mud)
The second way to repair a drywall hole is to cut out a square piece of
drywall, from stud to stud vertically.  A common wall stud is 1.75
inches wide, you need to cut the drywall back so that only half of the
stud is showing, and the other half is still covered by drywall.  Vertical
cut lines should be just past the hole edges to give a clean line, and no
studding will usually be present.  Cut a new piece of replacement
drywall (of the same thickness) to place in the square, gently screw in
the new piece by putting the screw on a slight angle into the exposed
studs.  Screw heads should end up just under the surface of the
drywall, now gently hammer in the edges so that they are concave and
mud over to just above flush.
Nail pops and dents!
Nail pops are screws and nails that are working their way back out, pushing the drywall compound
out which looks like a small bubble.  With a nail punch or screw driver, hammer the nail or screw
back in slightly, after this clean the area of loose material and you're ready for mud.  With dents
you'll want to scrape over them with a small putty knife (or hammer in) to make sure they are flush
with the surrounding drywall, again you'll be ready for mud.
Drywall cracks and taping seams!
Cracks appear in drywall from homes settling and can turn up years
after the home was built.  Digging out a width of the tape along the
crack, about an 1/8th of an inch deep is ideal.  Then brush any loose
particles from the area with a rag or your fingers, and apply mesh tape
along the crack.  Fresh drywall and replacement drywall needs mesh
tape as well, when taping try not to overlap any of the mesh tape, this
keeps face height as minimal as possible.  Now mud over the tape and
seam with about a half cup of mud on the 6" knife at a time.  It helps to
place two fingers on the back side of the knife as you pull it gently
across a repair, this helps guide the thickness of the mud being added.
Information on drywall holes, cracks and dent repair, ceiling
and wall prep.  Painting prep work is the most important
part of achieving a professional looking finish, and usually
the largest part of interior labor cost.
You'll learn about creating smooth drywall, making seems
disappear and all the uses of caulking.
Painting &
DIY Drywall Repair and Caulking!
Tri-County Painting
Farmington Hills, MI.
Interior washable walls with ceramic micro sphere technology
Ralph Lauren Interior Paints
Mudding with Durabond!
Durabond easy sand is a dry powder that you'll mix with water in a preferably stainless steel mud
tray, pour a small amount in the bottom of the tray and add small amounts of water at a time.  The
consistency should be similar to pancake mix and can vary slightly. (to thick it won't spread, to
thin and it will fall of the knife)  Durabond comes in a few different setting times, 5 - 25 - 45 - 90 are
the most common, I would suggest 45, it generally gives you about 15 minutes to work with before
it hardens.  Again, a 6" flexible putty knife is ideal, and use it as an extension of your hand.  Place
the handle in your palm and index finger on the one side handle on the blade and the next finger
on the other side of the handle, on the blade.  This gives you the ability to float the knife over the
patch area with varying amounts of pressure from both or either finger to leave a slight bulge in
the drywall mud.  Always try to go with the "line" of a crack or dent, by doing this the mud won't
pull out of the sunken area.  Start with a small amount of mud on the knife and place it in the repair
area, and gently pull it over the area.  Usually you'll have to flow the knife in a couple different
directions until you have a slightly raised area over the repair area.
Sanding a repair area.
Sanding sponges work great with durabond, use a fine and medium grit for the best results.  
Sanding should be done when all the mud areas are dry and have turned light grey.  Sand in small
light circles around the repair area, working into the center, but careful not to sand all the mud
away.  If you sand to much you can apply more durabond, and it's very important to feather in all
edges, this way the repairs will not show when a finish coat of paint is applied.  Use your fingers
and brush them over the repair feeling for ridges, if you feel any ridge then sand until it's flush.
Caulking is generally used for trim and in corner cracks of drywall,  caulk is great for making
seams and gaps in trim disappear.  Inspect all of your painted trim, if you can see any open gaps
between the trim and wall then caulk it and paint over.  Cut the tip off of the caulk tube on an
angle or straight, I prefer a straight cut so that you don't have to maneuver the caulk gun as
much while you're caulking.  If you have a hairline crack in a corner of the drywall you can apply
a small amount of caulk, then wet the end of your finger and rub along the caulk line.  Usually
you'll have to run your finger both ways until the caulk is smoothed out.  You should always wet
a finger and smooth out a caulk line, trick is to use just enough caulk and add more as needed.  
To thick of a bead will cause a mess, not only on your finger but on the wall and trim as well, and
after each run with your finger, clean your finger on a wet rag.
Benjamin Moore Professional Paint
Graham Aqua Born Paints