I would recommend telling your dad first since he's open minded and accepting. Ask him if he can keep it between the two of you until you're comfortable enough to come out to mom. Having one parent supporting you will raise your self esteem and confidence. It's nice to know you have someone backing you up and there with you. Later when you're ready, come out to mom. Having your dad by your side will help and probably encourage your mom to follow in his foot steps. If she's not accepting at first, at least you'll have your dad with you. But don't worry after some time a lot of parents come around. I'm sure your mom will learn to love you, she will just need time.
For me it was the opposite, I told my mom first, because I knew she would be accepting. Everything went well, it was kinda rough at first but with time it was fine. I thought for sure my dad would disown me so I only came out to him a year after I told my mom. Come to find out he's even more supporting then she is. I got extremely lucky I know.
I came out to both my parents through email. I figured it would be easier for me and for them. Through writing I could make sure to have all my thoughts down and everything I wanted to say. It also gave them time to absorb it before answering. Face to face you have to answer right away, sometimes people need time alone to get there thoughts/reactions together. But it all depends on you and your family. If you're brave enough come out face to face and think it's the appropriate way to come out than go right ahead. It's up to you and how comfortable you are.
I wish you good luck!
Coming out is rough and scary but remember to keep your head high and stay true to yourself.
In the end things will turn out fine.