What this guy ^^^ said, plus:
- Keep it simple at first. Make a small universe.
- Leave settings at default. Don't monkey around with them until you learn what they do.
- Let the AI run things for you. Maybe don't even take over a team for a while. Simulate and observe.
- Find the training videos on the OOTPD web site and watch them.
- Skim the online manual. Don't read it all; nobody does. Skim it for an overview of topics and concepts. Go back to it often and read details as needed.
- Have patience. It's a long learning curve but the GOOD NEWS is you can have a great time with very little effort or knowledge at first.
- However, the more you learn, the more time and effort you invest in this game, the more immersion, satisfaction, and fun you will have.