How to start a conversation with a girl I like?

There’s a girl that I like on Instagram, I’ve seen her around a few times but have never spoken to her. She added me me about 3 weeks and she did like a few of my posts. I really want to speak to her but not sure how to start the conversation and don’t know what she thinks of me, she seems to be single but I don’t know if she’ll be interested in me. How can I start talking to her, would a simple ‘Hi, how are you?’ be good enough?

Where have you seen her around? That might be a good topic to start with. Otherwise, I'd just say: Hi (name), How's your day going?

If you end up getting good feedback, don't let too much time go by without asking her to get together, such as: I've been wanting to try out this new restaurant (name), and was wondering if you'd like to join me.

Good luck.

What do you have in common and where do you see her around? If she's someone at work be cautious. If this is someone at school then start talking to her about that. Start liking some of her posts or making pleasant comments here and there. Then once you have some rapport ask her to go for coffee. Never message vague random nonsense along the lines of wassup, hey, how are you, etc. Say something specific and ask her out.

I’ve seen her around a few times but have never spoken to her. She added me me about 3 weeks

Yes, start out with 'Hi, how are you?' Let the conversation take its own direction. Be easy going, natural, humorous without being goofy or unintelligent, witty without trying too hard and relax. Ask about her life and never bore her by talking too much about yourself. However, remain well-mannered, respectful, polite, never use foul language and be a gentleman. You'll be ok!

Go in with the mindset of establishing good friendship first otherwise you'll be perceived as a creep. Friendship first always. Get to know each others personality and character first and foremost.