Your watch is a pretty important decision. You'll have to see it most days, and it has to work with everything from a suit to shorts and a t-shirt. While in a perfect world, every man would have several watches for different occasions, that can get pretty pricey. I believe that watches, like all menswear, are not about how much they cost, but about how they look and how you like them. In my semi-limited experience with watch consulting, I haven't found an expensive, aspirational watch that doesn't have a satisfactory affordable counterpart.*
So for your one watch, pick well and don't settle. It's one of the few places you really get to distinguish yourself in an outfit. If it takes a little more time to find the one you want, it's okay, it's worth it for the amount of time you'll wear it. And don't be daunted by the choice, with just a few easy steps (below, the whole point of this post), your wrist will no longer be naked, and you'll have no excuse to pull out your phone when someone asks you for the time.
Also consider the width of the band. There should be a minimum width for men. Too thin of a band will throw off proportions of the watch and will potentially look feminine on your wrist. If this requires too much thought, take a look at all the selections and pick the most common width. You're not going to go wrong with the average, just stay away from extremes.
There's no right or wrong choice here, it's purely personal preference, but just know that if you're going to go with metal you have the extra choice of silver/gold/rose gold/mixed metals. With leather straps you have to choose between black and a rainbow of brown hues. When making these choices, think about what colors you usually wear and what look you're trying to go for and go from there. Then you get to consider a solid or embossed band. Solid is, well, solid, while embossed can come in many forms from geometric patterns to animal skins like croc or snakeskin. If these choices overwhelm you, go with plain. You'll never go wrong with plain, but if you don't think you're the kind of guy who can rock croc, you're not going to want to put that watch on.
After shape, consider size. Some men's watches come with very large faces. I don't recommend you go with one of these, as they can look bulky under clothes, make your wrist look awkwardly small and many times can dress down whatever you're wearing. Again, if you already have a nice go-to watch and you want to have some fun, then knock yourself out. Just know that a magnifying glass on your wrist should probably not be your only choice. On the other hand, if you go with a face that's too small, you run the risk of having a watch that's too feminine, especially if it has a metal band. The face doesn't have to span the width of your wrist, but if there's too much wrist around it, probably go a size up.
And finally on the face, there's color. This is another factor you must consider carefully. There's the run-of-the-mill gold, silver and white faces, but black is also popular now as well as blue. Though colored faces can add personality to a watch, again if this will be your only watch, choose one that will go with what you normally wear and can easily transition from lunch with friends to a cocktail party. Your neutrals like white and metallics will always do this, but the right black or blue face can work just as well. Any other color, choose with caution.
First and most basic are the hands. Some watches don't have a second hand, some watches only have one hand. Some hands glow in the dark, and some come in different shapes. Again, this is personal preference, but go with something you're not going to get sick of.
Next is numbers versus notches. Some guys think that notches only makes for a more sophisticated watch. This isn't necessarily true. If you're really using your watch to tell time, make sure you get one that you can actually read. Blackout watches or watches with neither notches or numbers look awesome, but when it comes to knowing what hour it is, maybe not so awesome. Again, go with what you want to look at every day, and don't overthink this detail.
Then comes dials. Men's watch designers love a good extra dial....or 4 on the face, but this can make a watch face crowded or hard to read. If the extra dial is an alternative second hand, great. If it's telling you how many meters below sea level you are, maybe pass on that one. There are watches actually made for SCUBA, and you should get one of those if you're actually venturing under water. If you like the many dials look, you're in luck. There are tons of choices out there, but make sure that the dials aren't there for the sake of being dials and they don't detract from the look of the watch.
Knobs are next. These, like dials, can sometimes be gratuitous. Other times, the three-knob look really adds to the appeal of the watch. If you're going with a smaller watch, you should probably forego multiple knobs, but most average sized faces on a man's watch can support this look if that's what you're going for.
And after that, the extras can go in many different directions, and whether you should opt for or against them comes on a case by case basis. Yes, this is a big wardrobe decision. Whether you're buying this watch for yourself or choosing it as a gift for someone to get you, know your price point, know what look you're going for, then go through the details one by one until you find that one you're happiest with. And you don't have to do this alone. Most successful watch decisions I've seen made have been made with help from others. This should be fun, not stressful, it might just take a little patience!