Shyness is something you get better with with time, and at 17, you can't expect to be the most confident guy out there, but in my opinion they are things you can do to build your confidence and become less shy, you have to break it down to basics.
For example, if you feel good, you act good, you seem good. By this i mean you need to work on your ego, i am NOT saying become an arrogant bastard far from it, but i mean whats the main thing you notice from arrogant guys, CONFIDENCE, you need to develop a sense of this without becoming a snob.
How to build confidence and develop an non-arrogant ego? This is where you break it down to basics, there are many things that without you noticing, will affect your shyness, such as:
1.) Your clothes. If your wearing your worst top, your worst pair of trousers, naturally you won't be feeling that good walking down the street or feel like bumping into any girls let alone talking to them.
If your get in the habit of always making sure your wearing nice clothes, looking fresh/sharp, matching clothes or a good combination, you'll notice your body language as a whole changes, because you feel comfortable within yourself, it will greatly increase your posture just by doing this one thing, making you feel much more comfortable talking to that girl.
2.) Your hair, a lot of people confidence these days seem to originate from their hair, some of my mates can go from being the most cockiest arrogant guy when he's proper styled up his hair and feels like a million pound, then the next day he may be lazy and cba to do it and won't even go to the shop because he thinks he aint looking good. Find yourself a hair style that suits you and stick to it, its similar to the clothes points, you'll feel more confident by feeling comfortable with your appearance and lust reduces that shy feeling and will develop a sense of ego, looking in the mirror like "damn i look good" thats what you need.
3.) Smelling good is important, find yourself a nice aftershave that suits you and everyday when your going out put some on your neck, and a little bit on your shirt, every time a girl notices your aftershave and compliments it, its an ego boost, and a lot of girls LOVE for a guy to smell good, a lot of aftershaves to the right girl is seductive as well, hypnotising, look into it, imagine you bump into her and you go all shy, she turns round and goes mmm you smell nice what aftershave is it? instant conversation starter and breaks the shy barrier for you.
4.) No-one likes bad breath, and if someone turns round to you and says your breath reeks, thats gonna kill your confidence on the spot and make things awkward, last thing you want is to be trying to chat up that girl for her to cringe in front of you and say wtf have you eaten, whenever going out brush them teeth just prior to leaving, just having the knowledge that your breath is always smelling nice and not having to worry about it, will again reduce your shyness and improve confidence.
These are many more points to take into consideration but it will take me forever to explain everything to you, a lot of these points may seem like their stating the obvious but trust me its all very important and relevant. If you start mastering these 4 points, i can promise you, you'll walk into school/college or whatever feeling MUCH more confident, your shyness will be greatly reduced, remember if you feel good, you act good and seem good, its no lie. These 4 points will help you improve your posture and your sense of aura.
A lot of this you may already know or be using but i bet you never think about it, and thinking about it will great help. say your in class, you see her, you look at your hair - looking good, look at your clothes - looking fresh, remember you brushed those teeth - set to go, you smell your shirt - smelling handsome. you'll get a sense you've done everything correct and have no reason to be shy, now go say hello and display your newly found confidence.
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