Formal:
* Tu m'as fait sourire. (This is the most literal and common way to say it)
* Vous m'avez fait sourire. (If you are speaking to someone you need to address formally)
Informal:
* Tu me fais sourire. (This means "you make me smile", implying it happens regularly)
* Tu m'as donné le sourire. (This means "you gave me a smile")
* Tu as réussi à me faire sourire. (This means "you managed to make me smile")
Romantic:
* Tu me fais sourire aux lèvres. (This means "you make me smile with my lips" and is a more poetic way to say it)
* Ton sourire m'illumine. (This means "your smile illuminates me" and is a more romantic way to say it)
Other options:
* Tu es un rayon de soleil. (This means "you are a ray of sunshine" and is a very positive way to say it)
* Tu es tellement drôle! (This means "you are so funny!")
The best way to choose the right phrase depends on the specific situation and your relationship with the person you are speaking to.