DO consider the college that you're applying to - Is your school famous for artsy types or athletic ones? Is your school very Christian or is in non-religious? Keep these things in mind. If you want to go to this school, you might want to consider tailoring yourself to fit it more. However, if you have to drastically change yourself, maybe this is an indicator that the school isn't quite for you.
DO NOT be afraid to contact the admissions officer beforehand - It shows that you're taking initiative with your future. Ask if they have any suggestions for what to wear, or if it even matters. If you feel the need, explain that you're accustomed to a more flamboyant mode of dress and ask them if you need to tone it down. Most of the time they're happy to respond.
For the whole look:
DO make the outfit appropriate for an interview - This seems like the easiest obsctacle to overcome. If you've been in this subculture for any amount of time, you've probably seen some article about how you can show off your Gothy side while still looking corporate. Reference those to see how you can look "adult" while still being Goth.
DO NOT misrepresent yourself - This is the true beauty of the college interview as opposed to one for a job: you have to be yourself. A college admissions officer is looking to build a community of people, they want to see the real you. If you have to hide your Gothness in an interview to get into the college, then (sad to say) it's probably not the right college for you.
For the accessories:
DO chose interesting pieces - Your favorite necklace, a ring with a story behind it, your "signature" hair band or anythingthat feels you. Chances are, your admissions officer is going to ask you some question about the way that you're dressed, so why not have a good story to tell? Your accessories can also hint at more than your Gothness, so use that to your advantage. If you're applying somewhere for writing, perhaps wearing a necklace with a dragon on it is a good hint that you're into more fantasy writing?
DO NOT fall victim to accessory overload - Have you all heard that Coco Chanel trope that, right before you leave your house, you should take off one accessory? I know that I'm one to fall for that accessory overload sometimes, but keeping the magpie tendencies to a minimum is probably a better idea.
For the hair and makeup:
DO spend a little time hiding any signs of stress - According to my dad, a Yale graduate, the admissions officers at Yale (and other Ivy Leagues) are trained to spend half of the interview calming the applicants and their parents and keeping them from stressing out. To counter act this at any school, and make yourself stand out, hide those little signs of stress: dark circles under the eyes, mussed hair (from stressfully tugging at it) and chewed up nails/nail beds. The idea here is to look collected and calm.
DO NOT use "standing out" as an excuse for Babybat makeup - I'm looking at you, lovers of eyeliner face-doodles. While you want to be true to yourself, you also want to look mature. Lets be honest, I'm closely acquainted with this scene and I still have trouble taking people with (usually smudged) eyeliner swirls down their cheeks seriously. How will someone who doesn't know Goth very well react?
For little touches:
DO clean yourself up a bit - Redo the chipped nail polish, swap the torn tights for fresh ones, give your bangs a trim, rub a little polish into your shoes. The last thing you want your admissions officer to think of you as are things like "messy," "dirty," or "unkempt." This is the time to be the most cautious with your appearance. You're making a first impression, make it the best one you can.
DO NOT forget a lint roller. Keep it in your purse and run it over your entire outfit if you can, right before the interview. This goes back to not wanting to seem messy, but honestly it just shows that you want to be taken seriously and that you aren't just a mad old cat lady. (Not that there is anything wrong with that...)
And that's all I have for you all, based on my own perception and experience with the whole process. I apologize for the small amount of menswear above, but most of the sets that I made for that seemed very similar to the ones I had made in my Back to School post. If you need to, you can reference those and tweak them with the above information to make an awesome guy's interview outfit.