My wife got pregnant sooner than we both expected and so I had mixed emotions about becoming a father. I had a different view of it when we got blessed with our succeeding children.
In the practical side of fatherhood, you must be prepared with your financial resources. This is in consideration of all the expenses that will come your way - starting from the very first meeting your wife will have with her OB-Gyne, to the hospital expenses once she gives birth, to baby needs and vaccinations, to schooling and more.
From the time your wife conceives the seed of your marital love, she will undergo a lot of changes physically and emotionally. Thus, you have to be strong for her and more understanding of her. The level of your emotional maturity would have to improve through time as your child/children are growing up. Taking classes or seminars in every season of your fatherhood would be ideal.
I can say, in conclusion, having a paradigm shift is the best preparation any man can take just right before he becomes a father. Truly, fatherhood comes with many challenges and responsibilities that can break one's heart and mind. But if you focus on its positive aspect and not its negative aspect, you are surely to be effective in it.