When asking a girl on a date, either via text, call, or in person, always pose it as a statement, not a question.
Example:
Simple, straightforward, unassuming. It lays out the time and place in one sentence. You aren’t asking her if she’s free or where she wants to go or what she wants to do. It is you who is going to do something awesome that night regardless if she’s available, and it would be cool if she joined you. Girls hate having to plan stuff, especially dates. It's too stressful and onerous for them. Take the initiative, be the man. She's less likely to decline or flake if you have things already planned out.
*Side note: The word "should" is so simple yet powerful. It makes her feel like if she doesn't come along, she's missing out on a golden opportunity to do something fun with you. It's almost like you are incepting the thought into her mind. You "should" use this word it as often as you can.