Sometimes you need them; sometimes you don't.

Oddly, I try to avoid colons and semicolons. They make sentences depend on other sentences in a burdensome way. I think they create difficulty for the reader. They create difficulty for me when I proofread: What is the mysterious connection between these sentences, that the author is trying to convey? And why doesn't he just say it outright?

Oddly, I try to avoid colons and semicolons; they make sentences depend on other sentences in a burdensome way. I think they create difficulty for the reader: They create difficulty for me when I proofread.