How to not come across bossy

How can I communicate without sounding bossy. For example, I live in a group home and when I am the one cooking dinner, no one except staff is supposed to be in the kitchen while I am preparing the meal (its a house rule). So when some one who has lived there at least 6 months walks in when I am clearly preparing dinner I say something to them about them not being allowed to be in the kitchen at that time, only it comes out like I am being bossy. I am not meaning to be bossy it just sounds that way. Any suggestions???

Try to be sympathetic to them. I mean, make sure they know the rule, but also tell them that you think it's silly afterwards (That's if you do, in fact, think it's a silly rule). Do this using an endearing voice and not a quick-fired response.