You'll need eyewear, but you can buy them from the salon you go to or they will provide them to you. My guess is they'll have several for you to choose from. Sunnies & Peepers are probably the most popular sellers, but there are a lot of other compliant styles you might get to choose from. They're just a few dollars, so no biggy.
The salon will also sell lotions made for indoor tanning. Only "indoor" lotions can be used indoors because "outdoor" lotions ruin the acrylic on the tanning beds. Some salons don't allow drugstore brands (even if they claim to be for indoor tanning), so before you take that route, make sure it's allowable at the salon you're going to. Many of the drugstore brands work the same as using nothing. Using a lotion will allow you to tan better and the ingredients are good for skin that's going through the tanning process.
You can wear anything you want, or tan nude. These days, most salons clean the beds after tanners instead of making the tanner clean after themselves. Whether you want a few tan lines or not is up to you...but skin that hasn't been exposed to UV light will be more sensitive at first. You can wear a suit if you want, but the lights can cause the fabric to fade over time. Most people that want to wear something use an old suit or their undies....thongs are great for minimal coverage. If you're going to wear something and you're preparing for a competition, try on your posing suit and then start trying on undies OVER the suit...anything that doesn't go outside the outline of your posing suit will be good to tan in.
Some things people take to the salon (some salons provide extras at their vanity counters): Lotion, deodorant, hair clips/bands, towel to cover their hair, lip SPF, SPF for tattoos, suit, hairbrush.