Well done for going out there and giving it a shot!
The compliment and finding out if they're single is absolutely right! However, you'll increase your chances of having a favourable interaction if you stick to some key points.
(1) Pre-frame.
The pre-frame is designed to both get her attention, pace her reality, and soften the randomness of the compliment.
For example, saying something like "listen, I know this is a bit random, but I saw you walking past, and I just had to say..."
What is does is explain exactly what's going on, show you understand what she might be feeling, and leads her to expect the compliment in a nice way, rather than just come straight out and saying "I think you're hot" or whatever it is.
(2) The compliment. It can be anything that suits how you talk. I say things like "gorgeous" because I'm a pompous git who actually talks like that. It may not sound congruent for you. "Hot" is a bit too general and vague. Better to verge on the side of "fucking sexy," and be a little bit different, then saying a bland "cute" and having her take it with a polite smile and start walking away. The BEST compliments are the ones that are truly GENUINE - the more you can actually say about what SPECIFIC features you like (her hair, her fashion, her sexy legs, her confident walk, etc.) the better.
(3) What to say after the compliment
This is the subject of many articles and videos. The important stuff, is
i. Don't wait for her reaction to your compliment. Say it, and move right along
ii. Introduce yourself and get her name. The simplest way to quickly make her comfortable in your presence and build rapport is to say her name to her a few times during your conversation.
iii. Find out stuff about her in a slightly different, unique, funny or interesting way.
=> "Where are you from?" "Are you single?" "What do you do?" are all perfectly reasonable questions, BUT, they are boring, she's heard them a million times before, and now it's all starting to feel like a bad pickup, instead of a unique, romantic moment. Instead of those, try
"I bet you're from Nigeria" when she's white
"You're either an architect, or a CIA sniper" to find out what she does
"How many boyfriends do you have?" to find out if she's single. Furthermore, keep going a bit and test whether, if she says she has a BF, he's actually REAL or not, if it's serious, and that kind of thing. Often girls will say they have a BF because they're nervous or shy, or they'd kinda seeing their ex and are maybe just looking for something casual. You don't know until you find out!
For more info on how have FUN doing successful daygame approaches, check out this free video series from the Daygame Guru and legend, Sasha
http://www.sashapua.com/get-my-free-vid ... t-approach