Review your spec script abstracts. These are several sentences describing show concepts, briefly touching on the A and B story lines.
Play around with your abstracts. Perhaps one A plot from one abstract would work better with a B plot from another. Once you find the best combination, you are ready to start your outline.
Begin with your cold opening. This is the opening scene of your show. Not all shows have cold openings. But if yours does, outline it and decide what plot elements to introduce, if any.
Start outlining your first act.
Write where and when scenes take place so you get a sense of the passage of time in your script.
Write briefly what transpires in each scene. One to two sentences will do. Be sure to include character names.
Begin outlining your second act once your first is complete. Use the same method, being sure to record time, place, characters and a rough, two-sentence description of what transpires. Think of how each scene forwards the plot, whether in the A or B lines. This will make your outline more useful when you use it to write your actual script.