The Writer's Dilemma

I have been thinking a lot about writing because I have a story idea that I want to develop. Creatively writing rather than blogging is a newer thing to me, especially in long form and I am thinking about the right ways to approach it.

At least I have the first step in mind, a general story outline. I know the points that I want to touch on and somewhat of an idea what I want the end result to be but that leaves the lines connecting the points undrawn, and I'm pretty sure it's not just like connect the dots. Where do I go from there? I don't know where to approach.

I wrote out a short plot synopsis with important details included but that still doesn't get me started writing the piece (what I want to be a screenplay) as a whole. Where do you begin your attack?

I feel like I can't start with the beginning because I am not sure how I want it to begin and I feel uncomfortable writing some random scene in the middle because that just seems out of place. So if I can't start at the beginning or the middle or the end, where is my jumping off point?

AND another thing, this whole writing something that others will read and possibly eventually see is to me a practice in temporarily inflating one's ego. I have an ego, but it is based on very little and seems to only be able to go down from here. To write something with the presumption that other people will find what you have to say interesting is bold and I don't know that I am that bold.

If any of you are curious my approach to developing this story/characters is going to be writing a series of short stories about specific characters until I feel comfortable taking it a step further. Writing is work and I am not used to working. I am slowly realizing that the writing process involves a bit more than just sitting at a coffee shop and typing away and that I am in for a long process.

I am open to any advice, but just thought I'd express what I am thinking about this thing that I plan on doing.