Welcome and here is my thoughts. Plus 1 on looking up information and asking questions. I never did that and learned the hard way. Now that I've been riding 5 years I have some exp.

First Do not ride on the sidewalk.
Always wear a helmet.
Do not be foolish.
get as much info as you can.
ease into it. the more you ride the more it will become part of your life.
Eat the right foods, like meat, veggies, and drink lots of water on hot days.
If riding at night get a front and rear light. The more traffic your with the brighter you want it to me.
Be careful at intersections. I have been crossing 3 sets of stop lights on my afternoon ride into work and I cross more the 7 on my morning ride. There would be a lot more if i rode more. Ive never had a problem with letting all the traffic go first and then proceeding after. But make sure the light is still green and make sure you can stop somewhere like a parking lot, driveway, or wait on the sidewalk until the traffic clears. Also if you are behind a larger Truck make sure you can see the person in the opposite lane as they often will want to turn as soon as the last car goes through the intersection. It is important to make yourself visible at that point in time. good luck.