I found a neat site by googling "motorcycle touring for beginners". He listed most of the things already suggested. One thing he stresses that the weather changes very dramatically at highway speeds, you have to come prepared for all the extremes, from very hot to very cold. And very wet, too!
Here's things I don't leave home without:
1. sunscreen, and coat that neck good.
2. two Aerostich triangle neck thingies - one that absorbs water for cooling, the other fleece/goretex for warmth and dryness. They're small to pack, and add a lot to the comfort. The cooling one can also be used to clean off your helmet visor.
3. a good lip balm. I like Kiehl's. It even comes in 2 nice tinted shades,for us ladies, and it it's in a tiny tube (not a stick that melts in the heat!).
4. he recommends a long sleeved cotton tee under your gear, and lycra tights (full length). Haven't tried this yet, but will on my next longer ride. Another alternative is bikershorts, you can buy these cheap, or go for the higher-end Dri-max or Cool-max. Wicks moisture, prevents chafing.
5. foam disposable ear plugs. Just bought 100 pairs on Ebay for 14 bucks (as compared to 5 dollars for 6 pairs at the local Home Depot!)
6. Swiss Army knife - but then, I never leave home without it.
7. sunglasses that work okay with your helmet. Polarized helpful.
8. A tank bag. But don't put any credit cards near the magnets!
9. Water bottle - especially good if you can grab it while riding (but without losing control of your bike)
8. Duct tape, and some of those plastic tie thingies. You can do a LOT with these!
9. cable lock, if you want/need to stow your helmet and gear and leave the bike. You can lock the gear to the bike, at least.
10. Energy bars, or other portable, high protein foods, like almonds. Try to go easy on sugar stuff, which gives a quick boost, but then crashes you.
My biker brothers prefer jerky and trail mix type stuff.
