Write your story. Get it down on paper. Then let your friends - those you can trust and who will give you honest feedback - read what you have. Be able to take constructive criticism well and always keep an open mind. Sometimes it's difficult hearing the truth, but in the end, if you keep an open mind and you can use the feedback correctly, then your book is only going to be better. If writing is your passion, go for it, give it your all and above all else, enjoy what you do.