I open the clasp with the tip of my thumb, hold the connector part with my other hand so it's held straight, not by the chain so it's dangling or anything and so I know how the hole is oriented if that makes sense, then clasp them together, front or back depending on my mood. I don't look at it while I do that. I don't see how you could, unless you have antennae eyes, which I hope you don't.
Basically, just practice

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