Dress smart casual. You need to feel confident and look this way. You will inevitably interact with people if you do street shooting, and they will judge you by the way you dress. You need to command respect. I know American dress code is more liberal than Europe, but still - good collar shirt, smart jeans or trousers, the best is to look like a middle class, well heeled carefree tourist in places where are lots of tourists or just to blend with general public. If you dress very well, most reactions to your occasional friendly intrusions into their "public privacy" will be milder. Behave appropriately. Smile, enjoy yourself. Be ready for a joke or two. After all it is fun.
Do not wear photo belts or big photo bags. And god forbids photo vests, rucksacks, slings and the like. The Traveller summed it up very well. Like a clown with bells and whistles, that's how you will look. You do not need it. The best is to have a stylish, not really small ( that would look weirdly feminine) but not big and bulky bag. The sort of bag men carry every day to the office. Try not to look like photog. Still you will need some bag with your D810, because street shooting is time consuming, you will walk around for hours and will want to get some lunch or a cup of coffee in a cafe, the bag is handy. I use a non obtrusive khaki colour Lowerpro messenger type. The is place for my camera and an extra lense. I usually have a banana there instead. Or an apple. Or a small water bottle. Or nothing. What I always have is two spare batteries and some lense cleaning stuff, just in case. If you go out for a short time, you may just take a camera and nothing else.
Most of the time you do not need any spare gear apart from a battery. Do not take extra lenses. Especially at your current stage, you do not need to change lenses, choose one you feel most comfortable to shoot with and try to get to grips with it. You need to work on your technique and shooting routine, to figure out your preferred distances, compositions and framing styles. If you start changing lenses, you will get confused. Stick with one lense for a couple of months. 35 mm is an excellent fixed lense for street shooting. I often shoot with 18 mm on crop (27 eqv on FF) , but it is not for a beginner, a difficult focal range.