Beginners play atari
The Go proverb "beginners play atari" is much like the chess saying "patzer sees a check, gives a check". Beginners often find it difficult to resist the urge to give atari, even when the atari helps their opponent. In particular, one should beware of situations in which an atari may be aji-keshi or a thank you move.
Don't do something just because you can. Have a reason for doing it. And, no, "to capture the stones" is not enough of a reason. Why do you want to capture those stones?
The Japanese from which this proverb is probably derived is アタリアタリはヘボ碁の見本 ("atari-atari wa hebo-go no mihon"), which has a nuance vaguely different from "beginners give atari", something closer to "atari-atari is bumbling go at its best". A variant is アタリアタリはヘボ碁かな ("atari-atari wa hebo-go ka na", "see too many ataris, smell a bumbler").
Imagist: I don't think this is worthy of the negative attitude that it is associated with. Of course, you don't see dan level players playing atari on every stone they can, but for a beginner, this is okay; if they are playing atari too much, at least they are seeing it. It's just a stage of learning.
The same can be said of other techniques. For example, when I first learned the squeeze tesuji, I played it often; too often! Eventually I came to understand when it was appropriate and when it wasn't, but if I hadn't tried it a lot I wouldn't have figured that out.
In general, this can be thought of as a three-step process:
- Learn about a technique.
- Learn to apply the technique.
- Learn when not to apply the technique.