Tips for biking 30 miles to school (4x a week)?

You need a very good quality bike to commute that far every day. At your height, you should be consulting a good bike shop. Tall people can have difficulty ordering bikes online and finding a good fit. For that distance it would be very important that your bike fit you properly. A touring bike makes a very good long distance commuter as it has the proper fitting to mount a rack and to install mudguards which are almost essential if you ride in wet conditions. You absolutely need gears if your route is hilly, and you also need to have the tools you might need to repair problems you might encounter on the road. Riding that many miles, your bike will need frequent maintenance, lubrication, and cleaning. I commuted about 2/3 the distance of your commute 5 days a week for 25 years. On average, I spent $200-$300 per year on replacing parts that wore out. Tires, tubes, brake pads, chains, cassettes are all wear items that have to be replaced. Figure 2 sets of tires, 2-3 chains, a cassette and a set of brake pads every year. In addition your bike would need a full overhaul a couple of times a year which could be costly if you can't do your own repairs. You won't save any time compared to the bus, even once you are in shape you will probably spend at least 4 hours per day on the road. As for snow, it really isn't practical to think about riding that distance in sub freezing temperatures, and snow covered roads really slow you down, figure an additional hour each way on a snowy day. Winter also presents extra problems dealing with cars, they simply don't expect cyclists on the road, and days are much darker.