Yes, most people are here to study seriously.
Keep looking for a suitable person.
One thing I recommend, is to put your best effort first, demonstrating first of all that you are willing to help others learn Portuguese - for example, answer questions in the 'Answers' section, and correct people's 'Notebook'.
Then also show your seriousness in studying English by applying the rules that you already know, and don't take shortcuts, which give an impression of not really caring. For example instead of ppl write 'people'. Otherwise to your partner it looks like you make 'mistakes' that are actually not mistakes but are lazy shortcuts, and the person gets frustrated trying to help you as they have to correct each one. Another example is not capitalizing the E in English. It is an actual error, but how can the person know whether you are making a sincere mistake (like many people make) and they have to correct you, or you are just being lazy? Being serious will actually increase the chances that a serious partner will choose to study with you.
I hope these tips will help you.