First of all, I was applying for a long sejour student visa in San Francisco, and rules are different from consulate to consulate and from one type of visa to another (i.e., work vs. student vs. tourist). But I think these guidelines should help any application.
1. Make sure you have every single document on the list that the consulate gives you. The list should be available on the consulate website. Most important is your passport and your application. You won't be let in the door without these.
2. Copy EVERYTHING. Even if the list given to you by the consulate doesn't specifically say that you need every document copied, do it anyway.
3. Keep everything organized. Make one folder for original documents, and one for photocopies, and tab things so that you can find them quickly. I was standing at a little window, not sitting at a table as I expected, and it made it difficult to sift through papers.
4. Apply to CampusFrance early.
5. Do everything as early as possible, in fact. Make your appointment early, get as many documents as you can as quickly as possible. My roommate was working on getting stuff put together for her Spanish visa and the process was much more stressful than mine because she didn't get everything done as early as I did (not entirely her fault). Above all, don't procrastinate.
5. Buy your plane ticket before going to the consulate -- if you're worried about being awarded the visa, buy insurance on the ticket. For a long sejour, you only need a one-way ticket to France.
6. Try to speak in French with the people there. I don't know if this actually helped me, but even though I misunderstood him when he told me to put my four right fingers on the finger printing machine (come on, I don't even know the word in English), it seemed to make the appointment go much smoother. He chatted with me about where he was from and the programs I'm going to, and then he told me that Paris would be beautiful without Parisians. I won't say if I agree or not. At least say "Bonjour Madame/Monsieur" as a greeting and "Bon journée Madame/Monsieur" when you leave, even if you know no other French.
As long as you come fully prepared with every document you need, your passport, and a copy of everything, you should be set!
