I see genealogical queries in many places that could be much improved. You want to give enough information that someone working on the same family would recognize it and read the query. After all, what is the point unless you get potential relatives to read it.
A good title gets attention. For example if I was researching Emma MacKenzie who lived in New York around 1890 to 1920, I'd be very like to read a query that was entitled "Emma MacKenzie, New York, 1895" than something simply called "MacKenzie family". Gives enough in the title to make it interesting enough that your potential relatives will read it. People are busy and are unlikely to read further unless they have reason to believe your query is worth a bit of their time.
Try to keep it to the point. You can share details by email when someone writes you. Any given name unless it's really odd will most likely occur several times in an area so be sure to include facts like spouse, children and approximate dates. Remember that the potential relative that reads this may know either more or less than you do. Don't make the query so long that people give up before getting to the essential facts.