Anticipating a child leaving home is stressful, so be kind to yourself. And anticipate that your child might be excited one minute and concerned the next. There are two people to take care of here: you, and your child. Helping him or her to be prepared might make you feel better too. (To keep things simple, I'll use "he" or "him", but I mean either.)
 
There are some basic things your young person needs to know.

• Money – he needs a bank account; to know how much is in it; to have a budget for his expenses; and a checkbook, debit card and credit card. (An online app may work best for his budgeting. Establish what you are contributing, if anything, and help him understand about credit limits and debt.)
• Laundry – does he wash, dry and fold his laundry? Can he iron or take his clothes to the dry cleaner? (Does he know which ones need to be dry cleaned?) 
• Cooking – Can he cook at least simple food, like eggs, rice, potatoes, spaghetti, vegetables or hamburgers? Does he eat fruit? (Even if he is eating in a dining hall, he should still know these things for after college.)
• Cleaning – Does he wash dishes, clean the bathroom and kitchen, and vacuum or sweep occasionally? Does he change his sheets and towels occasionally? (I know, they are teens, but really…)
• Health care – Does he know simple remedies for colds and flu, and when to go to the doctor?
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Reviewing these things, or teaching them to him now, is something you can do to prepare him and relieve anxiety for both of you. Have him use these skills for several months before leaving, so you can supervise, correct, and approve. Have him cook at least one meal a week for everyone in the house. He should sort, wash and fold one load of whites and one of colored clothes every other week (or as needed.) He should make one bank deposit; write one check; use the debit and credit card once a month, with your supervision. Help him construct a budget and discuss limits and ways to save. Once a week he should clean a room where you live, rotating between rooms. He should wash dishes and clean the kitchen after dinner one night a week. And talk about what he can do about his own health care, and how to find a doctor (not the hospital ER, unless it is a crisis.) This practice will assure that he has the basic skills to survive on his own.
 
By now I hope you have taught him how anticipate and navigate lifes' thornier issues: good work habits, drugs and alcohol, safe sex practices, etc. These are values and practices he has to develop and use on his own.
 
One other thing: letting go a little at a time is good for you and your son. You’ll both be ok.

Poor communication is overwhelmingly the most common complaint I hear. There are several components of communication you can change.

1. Content: The content of your communication is what you want to talk about. If the content is about a sensitive topic (the other's family; religion; child-rearing; sex or money) pay special attention to the factors below:

2. Timing: If the topic is new, important or sensitive, choose your timing carefully, so your partner can give you his or her full attention. Times to avoid: during the morning dash out the door; right before falling asleep; when electronic devices are on. You might ask "Is now a good time for me to get a few minutes of your attention to discuss _____?"

3. Tone: Avoid sarcasm! Do not yell - speak evenly at moderate volume. Remember also that posture and gestures are the "tone" of body language. Don't point fingers or stand over the person you are speaking to. Instead, sit back in an arms-open position.

4. Phrasing: Choose your words carefully. Talk about YOUR thoughts and feelings. Do not presuppose that you know what your partner thinks or feels. Avoid absolutes ("I never"; "you always"; "no one"; "everyone", etc.) Ask questions (in a non-sarcastic tone) that will invite the other to participate in the discussion. For example: "What are your thoughts on...?" or "Can you help me understand why you feel...?"

5. Listening: We have 2 ears and one mouth. Try to listen more than you talk. Paraphrase back what you hear: "ok, so you think that I ___. Did I understand correctly?" By paraphrasing, the other knows that you listened, took it in, and are treating the discussion seriously.

Remember that changing the way you communicate will take time and practice. Be patient with yourself and others, and give yourself credit for trying!