Your first serious watch should be a pleasure to buy, not a source of anxiety. A few simple principles will serve you well.
Buy the seller, then the watch
Authentication, clear photography, honest condition grading and buyer protection matter more than a slightly lower price from an unknown source. A trustworthy seller removes most of the risk.
Set a budget — and stick to it
Decide what you are comfortable spending, all-in, before you fall for a specific piece. Factor in any duties or servicing.
Choose something you will actually wear
The best first watch is one that suits your life — versatile, comfortable and a joy on the wrist. Resale value is a bonus, not the point. Buy what moves you, from someone you trust, and you will rarely go wrong.