Between coffee sips and pencil taps, I like to treat a clue like a tiny mystery. 'Celestial body' is one of those clues that can feel annoyingly broad, so I start by listing the usual suspects and matching them to the grid: 3 letters could be 'sun', 4 letters often gives you 'star' or 'moon', 5 letters might be 'comet', 6 could be 'planet' or 'nebula', and longer fills include 'satellite' or 'asteroid'.
If the crossing letters are friendly, I let them guide me. A pattern like N almost always points to 'sun' or 'moon' depending on length; A R frequently becomes 'star'. If the clue had a hint like "burning" or "luminary," I lean toward 'star' or 'sun'. If it sounds more dramatic or poetic, 'planet' or 'satellite' might fit. I also watch for pluralization in the clue and for crosswordese like 'orb' showing up in older puzzles.
When I’m stuck, I scribble possibilities and come back after a break — sometimes the right fit clicks with a crossing I hadn’t fixed yet. Personally I love the elegance of 'star' in a four-letter slot, but I’ve also had satisfying wins with 'comet' on days the theme called for transient visitors.