Choose a small simple project like a wall hanging or pillow to do. Use colors that you just LOVE.
Don't be too much of a perfectionist...it's your first and you want to finish it.
Take classes if you can. Quilters love to help newbies.
My first class, was to learn EVERYTHING and make a sampler quilt. No one told me to choose a small project. I choose to make a king sized quilt....never got finished...was overwhelming amount of work. Ended up not liking the color combination. And feel guilty that it is still in a box up in my closet unfinished....The good part of this little tale though is that I had a good teacher who stressed all that has already been mentioned like accuracy of measuring and cutting and I learned the basics of many techniques. Just learn from our mistakes. Start with a SMALL project that you will be able to finish and make yourself proud. Also use good quality fabric because it won't hold up well if you don't and you will be wasting your time, effort and money.