There is no doubt that chatting up girls can be nerve racking. Many of us do not even bother to act due to an overwhelming fear of rejection. With that said I posit one question to you. Are you going to spend your life thinking or doing? There is only one way to find out if a girl likes you or not and that is by asking her out. Even if you get all the signals you still have to ask her out. If she says no then you will not spend your days saying, "What if"
Nobody including myself likes to be rejected and hence feel unattractive. This of course dissipates your sense of self worth and hence confidence. As a result of which we drop our heads and make excuses.
With that said there are techniques you can employ to reduce the impact of being rejected or furthermore side step rejection all together. Our ego's can be frail even for those who seem the most confident. As a consequence you need to be more strategic in your approach as opposed to being tactical.
Tactics engage one method whereas strategy tends to lean more towards the bigger picture. When you are strategic your chances of success are greater over the long term. In a strategic sense your goal is to make friends and you will also understand that being that we are all different means that we all have different types, and if she says no, there are many reasons as to why she may have done so.
If you are not her type then that does not mean that you are unattractive and do not think either that those types of women are going to reject you for the rest of time.
Just like investing do not put all your eggs in one basket as this leads to imbalance. There are plenty of wonderful women out there you just have to find the right one and that ought to be your mission and you can start by making friends.
One powerful technique is to ask open ended questions that have general interest, besides politics, religion or sex. Another powerful technique is to listen and let her do most of the talking, you would be amazed at what you can learn when you listen.
To conclude never approach a girl from behind, do not get personal and do not jump right on the compliment bandwagon as it can come of as insincere right out of the gate. Get chatting first then say you enjoyed her company and ask if she would like to continue the conversation another time. Bottom line put your self in her shoes and be observant of what is taking place.