Sentence Clarity

Sometimes when I'm writing, I will jot down things I think of exactly how I would say them. This usually leads for things to be confusing, because I was taught you should not write how you speak. I think sentence clarity is the biggest problem for me when writing essays if I don't take the time to go back and change things around. I tend to use unclear pronouns such as this:

Unclear (unclear pronoun reference):

Larissa worked in a national forest last summer, which may be her career choice.

Clearer:

Larissa worked in a national forest last summer; forest management may be her career choice.