My 2 cents worth:

When correcting/criticising someone:

1. Don't make it personal.

2. Make it about the code and/or advice.

3. Use positive instead of negative terms.

4. Give an alternative and explain why it's better.

When being corrected/criticised:

1. Don't take it personally.

2. Remember it's about the code and/or advice.

3. If you are wrong, accept the criticism/correction gracefully.

4. If you are not wrong, use the first four steps above to correct the corrector.

And, for both, remember there are many ways to accomplish a task or solve a problem. Your way may be just one of many and it may not work in all installations.