I’m writing and I never know how to name my characters. Some people told me to come here ask for your help, because you’d know how to name her. She’s 16, she’s brazilian, brazilian and spanish decendent. She has dark blonde curly hair, white skin, brown eyes and she’s kinda short (155cm). My inspiration to create this character was [name_f]Selena[/name_f] Gomez, she’s my role model and I usually get inspired by her. My character is nice, smart, funny, usually acts like a little kid but just for entertain herself and the others. She’s funny all the time except when she’s mad at someone or something, or tricking or disturbing someone she likes. She’s good at everything she does, she always put her heart and soul or everything. She’s lovely, everyone loves her very easily. She makes everyone confortable all the time, everybody can come to her to play around or to ask for advice. And perhaps she’s not feeling well sometimes, she doesn’t disappoint who loves, and gets (or just pretend to get) happy and excited just to see the other person happy. She’s capable of giving up on everything to see the ones she loves happy. She gives her best as if she could take her place and take all the pain, but as she can not she turns into a better listener, and always knows a few words to comfort wounded hearts. She’s confident in who she is, she passes the confidence to believe in her. She’s always transparent and clear and objective, she knows how to be a friend and sister at the same time. She’s a little lazy, but she loves sports, loves acting, dancing an singing and she dreams to become an actress who also can dance and sing (she’s working hard to get that dream to come true, and she will). Her style, when it becomes to clothes it depends on her mood. She’s usually the romantic one. Dresses, boots, little bows in her hair, bracelets, necklaces, rings. And she loves the symbol of peace and little hearts, butterflies and stars when it becomes to jewelry. But, sometimes she’s more like “[name_u]Alex[/name_u] Russo” when it comes to dressing. Ahm, what more? She’s also a huge selenator, just like me. Her favorite color is purple and she also loves blue and teal. Her favorite music gender is R&B and Pop. She likes romantic comedy, romance, and drama movies. She speaks english, portuguese and spanish perfectly, Lives part of her live in [name_u]Rio[/name_u] de Janeiro ([name_u]Brazil[/name_u]), Madrid (Spain) and Los [name_f]Angeles[/name_f] and [name_m]New[/name_m] [name_m]York[/name_m] (Usa) And, I guess I already gave you enough of her. I need to find the perfect name and the percect last name to go with. 
I think what makes this so difficult is the character you described seems too perfect. That makes the character hard to relate to and thus hard to imagine a real name associated with her. But personally the character you described sounds a bit preppy so maybe a [name_f]Kylee[/name_f] or [name_u]Aubrey[/name_u], unless you want to play up the Latino. The top baby name in brazil in 2011 was [name_f]Julia[/name_f]. [name_f]Hope[/name_f] that helps
Sounds like a [name_f]Mary[/name_f] [name_f]Sue[/name_f] to me.
I’d think about giving her some flaws before you give her a name 
I feel the same way. She is too perfect, no one is that perfect. I’m sure even [name_f]Selena[/name_f] Gomez is annoying in some ways
So that’s a lot about her (yes, too-perfect, but that’s your own prerogative) personality, but what’s really important when it comes to naming a character is their background; after all, it’s her parents who named her.
With that in mind, who are her parents? What I mean by that is, which background is the strongest in her family? Was she born in the US? [name_u]Brazil[/name_u]? Spain? She’s lived in all of them, but what her parents’ plans were would change what kind of name she gets. I assume she’d use a name that works well in all three languages of English, Spanish, and Portuguese since her parents seem to like moving around quite a bit (only to big cities though, it seems).
Names that I think could work in all three countries based on a quick search on behindthename:
[name_f]Angelica[/name_f]
[name_f]Angelina[/name_f]
[name_f]Beatriz[/name_f]
[name_f]Camila[/name_f]
[name_f]Eliana[/name_f]
[name_f]Esmeralda[/name_f]
[name_f]Isabel[/name_f]
[name_f]Laura[/name_f]
[name_f]Lorena[/name_f]
[name_f]Raquel[/name_f]
[name_f]Teresa[/name_f]
I’m sure there are a ton more, but these were the ones that showed up.
My favorites of those for your character, based on what I know, which doesn’t include anything about her parents’ taste in names, would be [name_f]Angelina[/name_f], [name_f]Eliana[/name_f], [name_f]Esmeralda[/name_f], and [name_f]Isabel[/name_f]. She’d probably go by a cute nickname among friends, right? And names like [name_f]Eliana[/name_f] and [name_f]Esmeralda[/name_f] have the “special” and “unique” factor you’re probably looking for, while [name_f]Angelina[/name_f] has the whole “angel” thing going on. And [name_f]Isabel[/name_f] is just a good name in general.
I can’t help with surnames much, but the first thing you should decide is if it comes from her Spanish or Brazilian heritage. While Spanish and Portuguese are similar languages in many respects, the naming conventions are quite different. Make sure you look up how Spanish and Portuguese surnames work, and think about if and how they would “Americanize” their names in the US. Spain has requirements for how surnames are registered, so look that up. No matter where your character was born and which system her parents used for her original birth certificate, if she had her paperwork done in Spain while living there, it’s something she’d have to deal with.
I must admit that [name_u]Ren[/name_u]'s comment about her being a “[name_f]Mary[/name_f] [name_f]Sue[/name_f]” made me laugh. If you don’t know what a [name_f]Mary[/name_f] [name_f]Sue[/name_f] is, look it up. I know a good [name_f]Mary[/name_f] [name_f]Sue[/name_f] litmus test. [name_m]Just[/name_m] a tip from someone who used to write, and still sees a lot of, characters like yours. ^^ My [name_f]Mary[/name_f] [name_f]Sue[/name_f] Detector radar was going through the roof reading your description, haha. Not a bad thing necessarily, but definitely something to be aware of when dealing with characterization. It’s your character, so you can do what you want, but be aware that people [name_m]WILL[/name_m] call you out on it. There’s a long and difficult war against [name_f]Mary[/name_f] Sues going on. Tread carefully.
[name_f]Hope[/name_f] that helped some. Good luck!