See How I Built Our Rainwater Harvesting Systems.

For a large project like this, I take my time. First, I watch a LOT of videos to see how it is done. Find out what part of the job that I cannot do, and find a way around it to do. I don't care about how it looks, nor perfection. I may end up with some scratches or dents, or small leak in the rain gutters. I don't care. Functionality is my goal. If it works, then I am happy. Second, I plan how I am going to accomplish each step of the project. If I have a good chance of success, then I go ahead with the project. If I get stuck along the way, then I may hire a helper just for the part that I am not able to do.