If you want to be a writer, there are two invaluable things you have to do often and well - read and research. There probably isn't anything I can think of right now that is more essential (besides butt in chair and write) and will show the weaknesses of a writer more.
The nice thing is the two of them can go together.
READ - Everything. All the time. As much as you can. If you have a smart phone, download the reading app of choice and when you are standing in line behind the woman who can't seriously need that much toilet paper, instead of playing Angry Birds, read. Kid is at a music lesson and you are waiting? Read. You are in a traffic jam and waiting...um...I guess it would depend on the slowness of the jam.
Don't have a smart phone? Take a book with you everywhere. Granted this is a little easier for women, but guys, be a little innovative :)
RESEARCH - I can't think of a single genre someone can write that doesn't require research. Lately I've been trying to figure out how long after an organ transplant people are taken out of ICU, what the odds are of organ rejection, who gets organs from where... There needs to be research for world building, standards for magical creatures, figuring out your own laws of the land.
Thankfully we live in the land of the internet, so research is significantly easier than it used to be, which means we need to do it more often and make sure our data is accurate.
What have you been researching that you didn't think you would need to? What has surprised you most when reading as you are embarking on the world of writing?