Do you have any distinct pronunciation patterns?
For example, some people always pronounce "s" as "th".
Personally, I have a tendency to pronounce "s" as "sh", if it's in the middle of a word (but not at the beginning or end of a word).
For example, understand, I would pronounce similar to undershtand.
I only know about this after listening to my own voice recording. It sounds different than what I thought I said!