Such a bad news

Hi there, how is it going today?
I am not in a good mood now because of a bad news from my boss that many keywords of mine such as "giày thể thao nữ" has been in low positions. Oh my God!
Actually, I don't understand the way that Google evaluates the keywords and website, I just do what I often do with other keywords and some good results has been seen. But now, I don't know how to raise other keywords like "giày lacoste chính hãng" up to the top 5 of search result of Google.
Jeez, I am so depressed that felling into confusing the way I am doing.
Okay, maybe I will come back to some forums and ask for help.
Thanks for reading these lines!