odds + ends
Socks have become a thing these days, but for an interview, keep them toned down. If you want to go fun, keep your socks in a dress color and go with a pattern. If your place of interview is a little more relaxed or creative, you might be able to get away with a fun red, yellow or other bright under the pant. Wear this trend with caution. What would be fun for a daytime summer wedding might not impress your future boss.
Just yes. You should always wear one. Always. The intricacies of the right or wrong watch are far too long for this post, if there is even a right or wrong. Watches are a personal preference and there are a lot of really nice and a lot of really questionable options out there. Just know that your suit will seem pretty incomplete without the watch, whether it's the only accessory you're wearing or not. It doesn't have to be a Rolex, but it should be on your wrist.
I'm of the belief that a belt isn't an absolute necessity, but a lot of people would disagree with me. I also don't necessarily believe that your belt has to match your shoes (especially if you go with an oxblood or lighter brown), but people might yell at me then, too. For these purposes, I'm going to say, if you feel like you need to wear a belt, make it match and keep it simple. The buckle should be minimalistic and should not attract attention to your waist, and neither should the hue of the belt, especially if it's because it doesn't appropriately complement your shoe color.
If you have a nice one, go for it! Nothing too showy or cheesy, but this little detail might tell your interviewer that you pay attention to the little things and care about polishing yourself up. If it's not your style, don't sweat it, it's definitely a take-it-or-leave-it accessory.
In the off chance you're wearing a french cuff shirt, keep the cuff links simple and understated. You don't want to send the wrong message at the first handshake, and too much glitz by your wrist might do that if the light strikes your cuff links just right. Opt for your plainest pair and don't think too hard about it, they're a means to an end in this case.
If you want to bring one, keep it sleek and nice-looking. An interview is no place for your dirty, nylon messenger bag. Opt for a leather choice that complements the other leather aspects of your suit and isn't so ambiguous in style that it will cause questions. A briefcase or simple messenger are going to be your safest bets. If you're bag-averse, go with a traditional padfolio. This is another matter of personal preference. There's a standard, but not a rule, so meet the standard and you're good to go.
a few last words
Jewelry. Take it off for an interview, or make sure it is completely and permanently out of sight. Jewelry will most definitely be part of a first impression, and apart from a wedding band, there is no reason it should be, because it will nearly always make you stick out in the wrong way.
And after all this preaching, you might be wondering what I ended up telling my brother to wear. His options were limited, so we went with a navy, 3-button suit (middle button only buttoned), a light blue button down and yellow tie with dark and light blue check pattern. He only had black dress shoes (I would have gone with something different if I had the choice), and of course a watch. His has a metal band, yours doesn't have to.
He got hired on the spot, so I'm not going to not say that my advice leads you in the right direction. When you're suiting up, use your head, look in the mirror and wear your interview look with confidence.