Tips to visitors for interview (US visa):
1) If you are coming by flight and going back on the same day. Try using washrooms at Airport to get fresh up. If you have much time more than 3 hours to the visa appointment, then relax at airport and plan to reach  our locker location at least 1 hour before your Visa appointment.
2) In free time before Interview: Read the DS-160 thoroughly. Check if you have appointment confirmation page and original passport.
3) Just before interview, avoid negative thoughts. Do not have a fight with your spouse or friends just before interview. Your state of mind might be disturbed. Keep all negative stuff after the interview. Avoid all distractions which might ruin your interview.
4) Make sure you have all printouts or photo copies with you before arrive for interview.  Mostly US appointments are early in the morning, there will be no shops open at that time.  Aprion digital lockers have printer facility, but better you bring all necessary printouts prior arriving. Use our printers for urgent or last minute dependency.
5) Take deep breaths "Inhale" and "Exhale" few minutes before the interview when you stand up in a queue.
6) Cross check if you are carrying passport with you. Sometimes, we carry all documents, but forget to take passport.
7) Do not talk to any one or gossip while standing up in queue for the interview. Do not concentrate on others, concentrate on yourself.
8) Always keep a smile on face while interview. Answer politely all questions with at-least two or three sentences. Avoid full length stories for each question. Avoid one word answers. Avoid lies. Speak truth.
9) Do not drink plenty of water. Just take enough water to mitigate anxiety and thirst. This is to avoid frequent urination. Always consume bottled /sealed water.
10) Avoid street food or unhygienic road side food to save money or avoid spicy food before interview. 
11) Do not argue much with anyone around you while you reach the interview location to save few hundreds of rupees. Keep your cool. Shell out few hundred of rupees if some taxi/cab person is asking for it or any auto walas asking extra amount. Your aim is to crack the interview, but not involve in unnecessary quarrels which might ruin your mood and may lead to a bad interview.  Avoid all such distractions, to save some money which might cost you more if you loose the interview.