Is it OK to compliment the dress of a girl to start a convo? Watch
That sentence....ummm no? at least imo I'd find that a bit weird
Rest of the sentence will put a girl off.
If you want it to be obvious you're interested in them then yes. If you're not interested in them that way, i think you'd come off as too strong. It's hard to compliment a dress in a way that you want to let them know you think it's pretty but you don't want to be with them.