My daughter and her husband are building a new house, and they're acting as their own general contractor. They have help from a friend who has experience in building homes and other friends are helping with the work. They'll get more house for their dollars this way and a whole lot of experience. It hasn't all been clear sailing. Little glitches pop up now and then, but for the most part, it's going along nicely.
The sheet rock is up now, so the shell is beginning to look like a real house. In a couple of months, they should be ready to move in. We've watched the progress through a couple of visits and many pictures sent through cyberspace.
We writers build our stories in much the same way. We draw up a plan, then sit down to write the first draft. It's the foundation. We add some details, and the walls are up. Toss in some more information that might be needed and our roof is on. We let it sit for awhile, then go back and revise where needed. The finishing touches that make a story polished and ready to submit. Just like the paint and varnish finish the house.
Whether you're building a house or a story, take your time and follow your plan. In the end, it will come out just fine.