みなさん、
こんばんは。It`s been very long since i wrote a grammar article. I was browsing through one of the online websites for Japanese teachers and it has something like this.
「日本語がお上手ですね。」「いいえ、まだまだです」
It seems that there was a research done on the public`s response to negative sentences nowadays. People tend to like sentences that is of avoidance.
I think you can change the sentence to something like
「日本語がお上手ですね。」「ありがとうございます。まだわからないところがたくさんあります。がんばらないと。。。」
I want to give credit to this sensei for writing such an article. Thank you, Kaki-sensei.
/Can