Given that advice on building homemade arcades is fairly easy to find, I'll be focusing on how to make yours look good. So maybe this is more, "How to Keep Your Arcade Cabinet off of Crapmame." Or sort of a "Martha Stewart Gives Advice on Arcade Machines," which I totally wish she would.
Step 1: Applying Control Panel Artwork
Though not the most robust option, printed graphics behind acrylic panels will look brighter and just pop more. I don't know the physics behind it, but clear acrylic just makes stuff look better. Printed graphics are much cheaper than vinyl decals, and give you freedom to design with as many colors as you feel like.
Cover the whole panel in double-stick tape, and leave one side unsticky.
Next, line up the graphics. Holding it up to a light helps with this. Tack down the sides with low-tack tape to keep them aligned.
-Tip: make sure to leave enough bleed to run off the edges, and enough gutter to keep your graphics from getting cut off (or close to it).
Peel back the waxed paper from the double stick tape, and carefully lay down the graphics. Move from one edge to the other, smoothing down the artwork as you go.
Now trim the edges. Poke a blade through the middle of a hole, and cut to the edge. Keep the blade pressed against the edge as you work your way around the cut. The edges are cut the same way, but they're less curvy, so you can relax a little bit easier.
Step 2: Applying Contact Paper
Contact paper adds plenty of style for relatively little effort, but it won't hide any nicks or flaws. Take care to sand and spackle before applying.
Make things easier for yourself by cutting out an inch wide, then trimming down. It's an old tip, but a good one nonetheless.
Use a light or sun behind the paper to keep it straight.
Press down the edges of contact paper to get a good visible crease before trimming. Keep the blade pressed against the wood, and try to trim contact paper in one go; don't stop and start midway.
Step 3: Roll Your Own Token Return Buttons
Token buttons help make your machine look that much more professional, but usually cost that much too. But if you have access to black spray paint, a laser cutter, and some scrap acrylic, you can make some of your own for much much less. (And since they're small, they make a quick cut for anyone who has to beg, borrow, or steal access to a laser cutter.)
For these, it's as simple as cutting out the buttons and etching the pattern in a mirror image.
Next, peel back the paper where you want the stencil, and mask off the edges of the plastic.
Give them a few coats of spray paint to get the stencil as opaque as possible.
Peel off the mask with a razor blade.
Step 4: T-Molding
T-Molding adds authenticity and style. It also uses vinyl, and is generally not something already in my shop. Black paint and varnish, on the other hand, seem plentiful around here.
Instead of vinyl molding, you can achieve a similar effect by rounding the edges of the panels with a router. Give them a quick coat of black paint, and protect them with a satin varnish. From a normal viewing distance the edges look pretty much the same, without one of the less friendly parts of the 70's.
Step 5: Reusing Joystick Bolts
If you're gong to use old joystick bolts, take the time to clean them up. I couldn't find joystick carriage bolts at the local hardware store, so if you're in a hurry you might not have much of a choice. After unsatisfactory progress from 20 minutes with a wire brush and a three-bold-holding-jig, I spent about ten seconds with a rotary tool and a sanding disk attachment. Afterward, I buffed them up with some 220 grit paper.
Step 6: Nail Down the UI
Spend some time customizing the user interface. If you've spent any time designing your machine, it's worth the time to make sure that the images on the screen match your style. Otherwise, whenever people come over to play it, they'll complain about the UI, and you'll have to make excuses for why it isn't done yet, and take it out over a game of Tetris.