Which is the best practice for writing fluently?
A. Create long sentences
B. Use a consistent sentence length
C. Combine related ideas
I would keep a daily journal, and write as if you were talking to someone. Keep in mind your grammar and punctuation. I would not do A or B because you can do those and still be a poor writer. Stick with C and have an audience in mind.
Writing fluidly is the act of finding your own "voice" and being able to re-create it in your reader's head. Once you do that, you can play with sentence length and the idea of stream of consciousness writing.