The best way is use the Keyword one time per 100 words which is about 3-5 lines. Use KW in first paragraph and title.
Then middle, and last paragraph.
If you do not go over an average of 1 keyword per 100 words, you will be in good shape for not being considered to be keyword stuffing.
Use your kw appropriately, with real content, not fluff.
You can use up to 3-5 secondary keywords to help avoid keyword stuffing as well.