Wikipedia:Common mistakes

Within Wikipedia articles, common mistakes to look out for:

Unwikified
Poorly structured ledes
Unencyclopedic writing
Use of Self-refs
Use of external links in text
Use of personal terms, first person references.
Typographical errors (spelling errors, grammar, duplicated words, etc)
Saving a new article with just the title and perhaps an opening statement or two. Because of the lack of info nor it being tagged, these are usually prime targets for new page police to attach speedy deletion or other tags. Instead the page creator should either hold off on saving the page right away or use the in use tag.
Signing contributions to articles