It's probably the way you're saying it. I always say it doesn't matter what you say, it's how you say it... so it doesn't matter, but it kinda does. I'll try and explain... you're using generic scripted direct style openers, although if that's really how you talk and you're saying what's on your mind then ok.
"I know this may be a bit random but you are stunning." - I'd leave out the first bit and just tell her. Of course it's random, that goes without saying. Don't draw attention to it. It's like you're trying to cover your ass incase she mentions it being random... which isn't a big deal. If she says this is really random, say "I know". Simple is best.
"I know this may be a bit random but your arse is amazing ( was gorgous guys )" - Nothing wrong with that, but again ditch the first part. You can't just say this kinda thing and try to go into a conversation though, and if you just say it then leave it at that you're only gonna get a smile and a thanks (or a weird look if she doesn't like ya). You gotta spin off from that, like... why did you have to wear those jeans, it's all I can look at, I'm usually more into boobs... it's distracting, if you come over later you're not allowed to wear them, it's too much, I'd have a hard time controlling myself as it is... etc etc. Just say whatever it is you're thinking, go wild. Don't keep it up for too long though, get ahold of yourself and make some actual plans... there's such a thing as too much flirting lol, remember to stay on track. Have fun with it but don't go overboard.
"dont take this the wrong way or out but you look amazing" - Same as before, get rid of that first bit. How would she take it the wrong way? It's a compliment. But you gotta tell her WHY she looks amazing. Any guy can walk up and say that, it's too generic and it can come across very insincere. What do you like about her exactly? Tell her.
Remember, never make excuses to talk to a girl or try and explain yourself or cover your ass. If you've got something to say, just say it. None of this "I just wanted to say..." or "I saw you from over there and thought..." or any of that stuff. Just do it. What you're doing is fine but you gotta take that little bit off the start and just get right into it. And if you're complimenting her, compliment her on specifics and be playful with it. Any guy can tell a girl she's stunning. You gotta tell her why, what you really like about her, that way she knows you're being genuine and not just firing a line at every hot girl you see. And remember, get to the point before you start to jabber too much! Have fun
