A good piece of advice that was given to me and I'll pass on to you, study the books first. A lot of people stress out over the FAA written test but there are many great resources out there, including free ones, that will help you pass. Once you pass the written it will help ease your mind and you can focus more on the flying aspect. I personally studied just the Gleim Private Pilot Handbook and then the Gleim FAA Knowledge Test book. Before I took the written I went online and found some free practice tests. Once I felt I was confident I could pass I went in and took the test.
You have several options on how to go about it, you can go through a flight school and take their ground school course, you can take an online course, or you can study the books the old fashion way like I did. The flight school option might be more expensive but if they have a set schedule where you show up and study that may help avoid procrastinating. The online courses are a great option and break everything down into sections with videos to help and a quiz at the end of each section to ensure you are learning. My dad took the Gleim online Sport Pilot Course and he really liked it. There are other companies that offer it too that I'm sure are just as good. I believe with this option you do not need a CFI to sign off to take the FAA written as you are endorsed by Gleim. Your last option is just to sit down with an old fashion book and read. You must dedicate time and not put off reading it. With this option you will need to get a CFI to sign off on you so you can take the FAA written. Everyone is different so go with the way you think you will learn the best.
Good luck! If you have any questions feel free to ask and many of us will be glad to help. I took the written last year and I'm hoping to finish up my license pretty soon here so everything is still fresh in my mind.