As far as image goes, get a cool haircut, lose the unibrow (seriously), go out and get some cool clothes. You can't do anything about the looks you have, but you CAN go to work on your appearance. Start a workout program if you haven't already. In my experience, NOTHING builds my confidence like a good workout. Not only will you look good, you'll feel great.
Smile a lot. Ask the cashier at the grocery store how her day is going. Say Hi to people as they walk by. If you want to have a good conversation with someone, base the conversation around them. Ask them questions about themselves rather than talking for days about yourself to make yourself look cool. If you think you're the only one who has insecurities, you're wrong. Everybody walks around with their insecurities, wondering about how other people perceive them. Remember, the only one who is critical of you is yourself. Girls are notorious for being the most insecure people on the planet, even the really hot ones.
Put a high price on yourself and your time. Find something in your life that you really enjoy doing (playing an instrument, martial arts, drawing, automobiles, etc) and run with it. Find some people in your area that share your similar interests and start hanging out with them. If you aren't enrolled in college, try out a community college. At college, everyone is really nice and people always enjoy a friendly face.
Don't take yourself so seriously. Learn to laugh about life's little things, and hold head high when you walk. Use good eye contact with people, speak slowly, and compliment them when you find something about them you find appealing. Focus on becoming a positive person, cast the negativity out of your head, and your insecurities about yourself will disappear.
We've all been AFC's at one point in our lives, but you can change that if you put the effort forth. It's not always a bed of roses, but becoming a DJ isn't about sleeping with a million women. It's about becoming the best man that you can become for yourself. Every woman dreams about being with a happy, confident, successful man who has his life together. You can't attract unless you are attractive. So get to work and become that man. Once you do, you won't believe how many women will be throwing themselves at you. I guarantee you'll meet some guys in your life who are great with women. You'll notice that all of them are happy guys who have their lives together.
As Pook said in one of his classic posts, "Your romantic life is an echo of your everyday life".