Question

Is the colon used properly in this sentence?...A positive side to that is: I’ve slightly increased my vocabulary, or at least I’d like to think.

Answer 1

May I make a suggestion?

Answer 2

No.

Answer 3

Yes it is. It introduces a sentence, meaning it creates context for the sentence that follows.

Here is a link for more information on the topic.

http://lilt.ilstu.edu/golson/punctuation/colon.html

Answer 4

Almost. The part before the colon has to be a complete sentence. Yours is not. How about this?
There is a positive side to this: my vocabulary has increased.