Things to look for:

- Native or C2 in the language you are learning

- Learning a language you are C2 or native in

- Willingness to communicate about goals and expectations prior to the actual exchange. I suggest starting the exchange via messages before going straight to skype. Get to know the person a little first and figure out what you each want to get from the partnership. If they can't handle a text exchange via messages, it's probably not going to be better live on skype.

As for why girls get so many messages, well some people obviously think this is a dating site or something. Ignore them. English speakers who are active on the site (male or female) seem to have a similar problem. I've had random messages from people who do not speak the language I'm trying to learn. I just ignore them. I'm not trying to be rude, but I'm also not going to provide free English lessons with nothing in return.

Good luck, I hope you find some suitable language partners!

I choose who I feel that he/she is serious about learning ..

It's hard to find a girl to practice with but it's okay there are many guys who seem serious and good ..

Unfortunately, after sometime of practising, I find out that most of them are just gamers and wanna pass their time .. Disappointing ..

There's something else .. you can practice for 2 or 3 times and after that you don't talk again and that's what happens often :D :)

Having a good partner can facilitate the procedure of learning, but it's not that easy to find a good one. :)

In my view, when it comes to finding a language partner, there are two things that are more important than the other ones . First, they should take the whole "language partner" thing seriously. In other words, they must wholeheartedly do care about it. Second, I think it's vital for us that our language partner should be from a type of personality that we like or at least  we can put up with! :D ;) If they are here, on italki, there's no need to bother ourselves so much, we can figure out how active they are just by visiting their profile. This way we are also able to obtain some information about their character and their behavior towards others by reading their comments and so on. This do matter between there should be a mutual respect between us, otherwise they're likely to be some of those who do not to turn up at the fixed date and time that we agreed on with legitimate reason.This might make us feel downhearted and discouraged and even give up the learning the language. 

Regarding the second question, why do you think it's specific to girls? This happens to many members regardless of their gender. It's more a matter of being beautiful and handsome. So it's not surprising that I testify that , as a man, I constantly receive lots of these type of messages everyday without fail. It's been so tiresome that I'm always thinking about deleting my actual account and creating another one with a photo of some guy who is not as charismatic as I am! :D ;)) Just kidding! 

I wrote a large comment and now I feel extremely drained, so I don't have energy to write my serious answer to your second question. So sorry! ;) 

Cheers!

I look for people who:

1) demonstrate thoughtfulness in the way they write 

2) have a similar approach to scheduling: I hate it when people try to call me right away after adding me on Skype, or just assume I'm immediately available or available at short notice. I much prefer someone who wants to set a time a couple of days in advance and shows he/she understands I have a million other things on my plate.

3) similar way of communicating: exchange at least a couple of messages beforehand to see if we might have a good chat.

4) not insistent that we immediately agree to be regular partners and talk multiple times a week for months. I don't mind at all if I talk to someone and it's a one-time event, or we talk a handful of times and leave it at that. 

As for the question about unwanted / unsolicited attention - people don't read, people feel free to behave obnoxiously when there are no repercussions, at least the type of people who send inappropriate messages. It's best to immediately delete and block them, and not worry too much about it.

Ana, então.... você sabe a resposta da segunda pergunta, né? Anyway, here is what I think...

1. Disponibility, mostly. I am not a very demanding person, so as long as the person talks to me I will respond. But then, I am not the popular kind of person in this website (man, not native english speaker etc etc) so my behavior is conditioned by those circumstances (myself not being very demanded).

2. Well: because we live in a world where there is male domination, machismo, etc etc etc, isn't it? This is the virtual, linguist equivalent of a catcall, I suppose.