Unfortunately this is a paradox of sorts. The best way to get confidence as a young lad, is to shag plenty of chicks. Ideally you will do this without 'falling in love', as when you 'fall in love' you no longer want to do all the shagging, and therefore don't get the confidence this brings. Whatever confidence you have accumulated will be utterly destroyed when the chick you fell for dumps you for a guy in an Xr2 Fiesta.
So, how to do all the shagging without falling into the 'love-trap'
This is tricky. For starters,
1. Never tell a girl you love her just 'to get into her pants'. Its not necessary when for the price of a bottle of wine you can avoid the topic altogether, and still get laid.
2. Don't go for the popular girls. They always expect you to love them. Those Bitches will get theirs later-on in life when they are the first to gain weight and look older than their years. At that point they are desperate for a shag and you can 'safely' slip them one without any fear of falling in love.
3. Avoid the religious girls. They have high expectations of love/commitment, and are notoriously difficult to crack without serious ground-work (often including use of the L-word). They also guilt you like crazy with their crying. So obnoxious!
4. Hang around drunk chicks. Drunk chicks put out and in the morning they will be even more embarrassed than you are. Ideal situation.
5. Hold parties and only invite chicks you are not attracted to. They will become more attractive as the night goes on (trust me). This way, after it goes down, and you've sobered up, you don't have any crazy idea's about 'going steady' with any of them, and any crazy idea's you had last night will just seem ridiculous in the cold light of day.
5. Try the ones that look 'off-beat'. They're trying to piss daddy off and you might fit the bill. Black nail-varnish is a dead givaway, as are tattoos/piercings. If they cut themselves you're in for sure.
6. Never call them 'afterwards', and if they call you, don't answer. It's often the easiest way out and it will enhance your reputation as a man who isn't looking for love.
7. Get a summer job at an 18/30 type resort. You're sure to get laid, and good luck falling for one of those slappers! Hah!
8. Try to pick girls you would NEVER introduce your Mom to (think, "OMG my mom would HATE this chick"). This prevents the relationship from getting too serious.
The beauty of my plan is that you are not aiming at girls who you may wish to fall in love with later in life, leaving this whole section to germinate and mature relatively unmolested.
Avoid Love until you're at least 30. That way you will likely only have your heart broken once. Remember that there will always be one that will do this to you, same as there will be one psycho that tries to kill you after you break theirs...