(shyguy77)
How do you practice anything? simply do it!
That seems like really unhelpful advice but honestly it is the best and only real good advice.
Use the universal chat-up line* to initiate conversation and then just talk.
Here is a thread with a long post by myself which may be good for you.
Weird Question
*universal chat up line is "Hi" it works every time!
(i love her)
Just invite her out to do something (that will be fun for BOTH of you), make sure she brings no friends.
When you meet her make sure you hug her, (you'll be very scared & ****ing your pants, trust me, but make sure you do it).
For the rest of the day when you need to get her attention, instead of saying her name poke her, put your hand on her back or shoulder & leave it there until you have her attention (it gets her used to being touched by you).
After you have finished that activity, ask her back to yours with a statement she can't say no to e.g. "Hey lets go back to mine & get something to eat".
Its alot better than saying, "would you like to come back to mine for something to eat or do something else".
Bung on a movie, and at the start (NOT half way, NOT at the end) hug her, by the end of the night you should get a kiss & only then should you even think about "asking her to be your gf".