I've done several motorcycles and typically you just want to be sure that you are not dressing the tires and being careful when your scrubbing as to not scratch anything.
Dressings are not good on tires, seats, footboards or pegs, hand grips, etc. I have used PB's World Natural Look with no slipperiness on my bikes. A serious buff n wipe after to remove any residue. I don't think I'd use it on someone else's machine.
Watch if you use a pressure washer also, some people have had issues with this.
Pressure washers are particularly bad news around wheel hubs. Even with sealed bearings you're asking for trouble. With unsealed bearings you can blast the grease right out of 'em.
Be careful what you use on the seats, you don't want to make them slippery.
Pure clean is the thing for seats.
Polishing clutch and brake levers makes them look nice, using anything that makes them the least bit slick is not good.
Some windshields are coated polycarbonate, some are Lexan, some are cheezy plastic. Know your material before you try to polish any imperfections. Machine polish a coated shield too aggressively and you'll find yourself buying a new one.. not cheap. Novus 3-step is a good and safe recipe by hand as is PlastX. Plexxus makes 'em shine and adds protection. Extra hand buffing and a jaundiced eye prevents smearing.
Uncoated aluminum wheels are a serious PITA. The rears not only pick up road grime but rubber and grease from a drive belt or chain and brake dust that can be caustic depending on the composition. They're frequently hidden by saddlebags and out of sight & out of mind. Keeping 'em clean and sealed when new prevents etching. It's almost impossible to get etched aluminum back without wet sanding. Best I've found for the worst of them is P21S polishing soap and Meg's Hot Wheels Chrome & Aluminum Polish. Some try Power Balls and other rotating aids... there really isn't any good and easy substitution for good old hand-rubbed, knuckle-scraping elbow grease, IMO. Microfiber gloves prevents bloodletting.
On late model Harley-Davidsons in particular, unless the owner sprung for the optional chrome spokes, they're cadmium plated and lose their luster fast. Try cleaning them too aggressively and you'll strip the plating right off. Test spot with a mild polish and if they don't shine right up visibly like chrome, they're cadmium. You won't get them to ever shine like new again so save the trouble.
Seats, saddlebags, etc need to be removed to reach nooks and crannies. If you're not familiar with a particular model have the owner do it. Setting fiberglass saddlebags on the ground, floor or driveway scratches the beejeezus out of the bottoms. Most people never see the bottoms but you probably don't want to induce anything on someone else's machine that you can avoid.
With the seat and sidecovers off most models will have a lot of exposed electronics. Be careful of using water around them and extra careful working around wires. You can't believe how crappy and unsecure some of the connections can be and it's a real headache troubleshooting a loose wire. I've used a light spritz of CD2 with a wipe down on black plastic components and it doesn't collect dust as badly as other dressings.
Get some wax or polish on wrinkle black engine or tranny cases and it's miserable trying to get off. Pig Spit or S100 Engine Brightener available at many shops darkens 'em up and has good longevity without burning off immediately. Many of the S100 products found in bike shops are P21S near-equivalents priced much cheaper. If you use S100 Cycle Wash, DILUTE it! Like TAW, spraying it on some things full strength, especially a warm engine, will stain. Scrubbing Bubbles and a soft brush will clean up nooks and crannies quite nicely.
Do many bikes, you need these:
Pimp Stixxx Motorcycle Detailing Motorcycle Polishing Tools Microfiber Towels Microfiber Cloths Biker Clothing Motorcycle Apparel
Very versatile and you'll find a lot of uses for them on cars as well. They're available under a more family-friendly name somewhereorother, the name escapes me now.
There's a product called Glare Pro Polish that makes a lot of claims I'm not sure I can agree with. One thing it IS excellent for is chrome exhausts. It shines up as good as any chrome polish and doesn't burn off immediately at high temperatures. I took a 2000 mile trip in all kinds of weather after polishing my pipes with it and when I washed the bike after the crud came right off and the product appeared to be still protecting. YMMV. Glare is available in many auto dealers with an OEM label. I've seen it labeled Honda Pro Polish as well as seen it in BMW auto dealerships. It can also be found on eBay under different labels. Priced cheaper too.
The absolute best tool for bike cleaning is a lift designed for a bike. You don't necessarily have to get the bike off the ground but easing the weight off the wheels so they turn makes cleaning tires and wheels a lot easier and more thorough. Working on an upright bike vs sitting on a sidestand allows better access everywhere. This can induce a tip-factor. A tie down strap anchoring the frame to the lift stabilizes things nicely, as long as you don't get overly aggressive. On a V-twin I loop a tie down right between the cylinders and lash the works down to the lift.
TL
Edit - almost forgot to address the most frequently asked questions re: cleaning bikes... to remove boot goo melted on exhausts use oven cleaner or Goof Off and 0000 steel wool. Brillo or SOS also works well. Cool or very slightly warm pipes works best. It may seem logical to try to clean hot pipes while the goo is soft but the burns can be incredibly painful. Don't ask...
