How do you tell a girl she's beautiful to make her blush?

Telling a girl she's beautiful in a way that makes her blush involves sincerity, timing, and the right phrasing.

Methods to Compliment and Elicit a Blush

Here's how you can compliment a girl on her beauty in a way that's likely to make her blush:

Be genuine and sincere: The most important aspect of a compliment is that it feels authentic. If you don't mean it, she'll likely be able to tell.
Choose the right moment: Complimenting her at a time when she's relaxed and receptive will make it more impactful. Avoid interrupting her or complimenting her in a way that makes her feel objectified.
Use simple and direct language: Overly flowery or complex language can come across as insincere or trying too hard. Simple phrases are often the most effective.
Focus on specific details: Instead of a general "You're beautiful," try mentioning a specific feature, like her eyes, smile, or a specific aspect of her appearance you find attractive. This shows you're paying attention and that your compliment is genuine.
Consider her personality: Tailor your compliment to her personality. If she's shy, a bold or overly forward compliment might make her uncomfortable. A more subtle and understated compliment might be better.

Here are some specific examples, keeping the above points in mind:

"You have a really beautiful smile. It lights up the room."
"I just wanted to say that you're looking stunning today."
"That color really suits you. It brings out your eyes."
"You have a way of making everyone around you feel comfortable and happy. That's a beautiful quality to have." (This compliments her inner beauty as well.)
"I really love your style; it's so unique and expressive."
If she's put in effort for an event: "Wow, you look amazing tonight."

Respect her boundaries: Always be mindful of her personal space and how she's reacting to your compliment. If she seems uncomfortable, back off.
Don't overdo it: Bombarding her with compliments can seem insincere and overwhelming. One well-placed compliment is often more effective than several.
Be yourself: Don't try to be someone you're not. Be authentic and let your genuine appreciation for her beauty shine through.