I'm of Chinese immigrant stock from both sides, born and raised in an Asian country some distance from China. I grew up using chopsticks once in a while at the table. Given my immigrant mixed-cultural environment, I'm definitely not an authority on the subject of Chinese chopsticks usage, let alone Asian chopsticks usage.
From my personal experience however, there is a correct way of holding/using chopsticks, in terms of finger positions. You'd be surprised to know that not all Chinese know this. (I only learned this myself when I visited an uncle in mainland China.) Also, holding the chopsticks 3/4 to 4/5 of the way up from the food end is considered more elegant. Any lower than this would appear gauche. Picking food up from the serving plate with the food end of the chopsticks is okay as long as you don't touch the rest of the food. People normally use the wrong end when serving food to somebody else's plate. It just shows courtesy.
Also from my experience, whether you hold the chopsticks wrongly or not, it's really no big deal. Not to my parents nor to our elders. Especially if you're not Asian. It's a non-issue. (In fact, some of my siblings hold chopsticks incorrectly.) Now, a non-Asian holding chopsticks correctly will defnitely impress those who know better and may even elicit admiring comments and questions as to how the person learned it.