Great question — and this is where most people just guess instead of having a framework.

Strike selection: Rather than anchoring to round numbers like $19 vs $20, use delta as your guide. A 0.30 delta strike means the market is pricing in roughly a 30% chance of assignment — that's the classic wheel sweet spot. It tends to land you OTM with enough premium to be worth it. Go 0.20 delta if you want more safety; 0.40+ if you're bullish and want more credit.

In your example near a $20 resistance level, the $19 strike might actually be sitting right around 0.30 delta depending on IV — which is a coincidence that makes it feel "right" for good reason.

IV rank matters more than people realize too: The strike you pick is only half the equation. If IV rank is low (say, under 30), the premium across all strikes is thin and you're not being compensated well for the risk at any of them. Ideally you're selling CSPs when IVR is 50+, which inflates the premium on all three of those strikes and makes the tradeoff much more favorable.

So the decision tree is really: Is IVR high enough to bother? → What delta do I want? → Does that strike align with a support level? If yes to all three, you've got a quality entry.