Planning for Actors

There will only be three actors in my film trailer. The antagonist, the man with the mask on. Then finally there is the male and the female. The body type for the antagonist I want to be rather tall and skinny, an ectomorph. The female I would like small, so they come across as being weak and vulnerable. Like a traditional teen slasher, I would like them to be blonde and large breasted but that is not a must have. And the male I do not have any specific qualities that they must have. What will be the hard part, is not finding the correct people, it is once I have done that, which is most likely the easy part, then getting all of us to find a time that is fitting for all of us and then for them to actually be good at acting. Which from people that have ever acted before in there lives, which is the most likely probability, they are not going to be good at all.