Getting the clay on the table
It doesn't really matter if you outline your stories, write every day or only when the muse calls to you. What really matters is that you get the clay on the table. A sculptor doesn't try to place his clay on the table in such a way that it looks great as soon as he has all the clay there. No, he plonks it down without caring much how it looks at that time. Only when the clay is on the table does he start to mold it and shape it, making that ugly lump into something beautiful. A writer should feel the same way.
You can't edit a blank page so you have to get your words out and then you can fix them up. As Anne Lamott says in Bird by Bird, you have to give yourself permission to write shitty first drafts (if you only buy one book about writing, I recommend Bird by Bird be the one). Don't worry about anything at this stage in the process. Just get it out. Punctuation, spelling, word choice, phrasing, even plot can be changed later. That's the shaping part. First you have to get the words down on the paper.
When you're getting that clay out, don't listen to the editor in your head, don't wonder what your aunt or your ex-boyfriend will think of this if it gets published. Don't even think of publication. That stifles you and makes you nervous. Don't let anything stop the flow of words and ideas onto your page.
My first drafts are usually full of this: [?]. A question mark in brackets follows anything I'm not sure of. Inside the bracket marks I will also put whatever I need to change/research/double-check later. I don't stop the flow to find out what the name of the character I introduced in the first chapter was, I just put [?that character who hit his mom?] there instead. If I use the same word four times in a paragraph or use a word or phrase I think sounds lame I'll write or type [?better word?] after it. If you wait to find the perfect word, those other words after it might not come out the same.
Lots of people say they want to write a book. I think many of them probably can. The thing that stops them from doing it is the idea that the writing has to be perfect. It doesn't. But it does have to be written or typed or recorded or whatever your method of writing is. So turn off the editor in your head, let yourself write a shitty first draft and get the clay on the table. It will work. Of course, that means that you will eventually have to get to the part of writing I hate, the editing part. But don't worry about that now. Just write and enjoy the freedom of not having to get everything perfect as you create.