A style sheet is a short document detailing the standard format that will be used in your pattern writing. For example, do you give round instructions "Round 1: ... Round 2: ..." or "Rnd 1: ... Rnd 2: ..."? Is each round heading bold? Do you capitalize the first instruction after the colon and end each instruction with a period? Are your stitch counts after an increase row indicated with parenthesis or italics? By using a consistent style and format across all of your patterns, you streamline the writing process and make the editing process go more smoothly (read: cheaper). You've already made all your decisions on how your instructions will be written out. Why reinvent the wheel if you already know your favorite syntax for bind-off instructions? Just reference your style sheet and copy the format in your next pattern.
Style sheets also increase your customers' confidence in your patterns. If they buy a pattern from you and found the instructions clear and easy to follow, they will be more likely to purchase another. By using a style sheet to ensure your instructions are consistent from pattern to pattern, you encourage customers to keep coming back for more as they know they can trust your patterns to be in a format they are comfortable with.
I can edit your patterns according to your style sheet, or if you don't have a style sheet and would like one, I can create one for you. Note that it is not a requirement to have a style sheet in order for me to complete a tech edit of your pattern, this is just something to consider. Usually a style sheet will pay for itself rather quickly, as it's much faster to check against the style sheet than it is to find an inconsistency, look through the whole pattern for other occurrences, make a decision on which style to keep, and then mark all conflicting lines accordingly.