Your first single does not need a perfect masterplan. It needs a clear finishing point and a set of checks you can manage without rushing. Pick a track that still feels like you after you have heard it too many times.
Before you send it anywhere, finish the credits and save the details in one place. Make sure you know who writes and performs each part, and agree on how the work should be described. If other people helped make the, have the conversation early. It is easier to clear up an agreement before a release than afterward.
Plan a simple way to show the track to people who may care. That could be a short video, a phhoto with a note, or a listening session with people who already know your work. Say what the track is and what made you want to put it out. An assured conversation is more useful than a loud announcement without anything to hold onto.
Hold back a little time for the unglamorous part. Listen through once more on different speakers. Check the artwork, file names, and links. Then pick a date you can support. A calm, finished release gives you more to stand behind than one you pushed out just to move on.
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