My friends?

My friends?
 

I'm a girl and if I want to say "my friends" including both guy and girl friends in Spanish. Is it "mis amigas" (to refer to my gender) or "mis amigos" (to refer to the gender of my friends)?

You would use mis amigos. You only need to worry about adjectives agreeing with your gender when you're talking about yourself.

it's mis amigos

We often use the word 'colegas', which can be masculine or feminine.
Las colegas / los colegas
Group gender, in case of a mixed group, is bound to be masculine.

"Mis amigos" should be applied both for a group of males or a mixed group. and "Mis amigas" for a group of females.

As far as there is not a neutral form of the verbs, Spanish uses the the male for plural.

Yes, I agree with all you, you must to use Mis Amigos. it's the best way to say my Friends in any kind of gender.