I’m going to assume that you looked up the appropriate representative to contact with these types of requests—but it doesn’t hurt for you to double-check that your queries are going to the right person. Once you’re certain that you’ve got the right contact info, make sure you are sending your queries via email only. Nobody queries through postal mail anymore, and phone calls can be annoying to busy reps.
Then, make a stellar first impression on the representative. Don’t think that because you’re talking to the rep and not the celebrity that you don’t have to put your best foot forward. These people get requests from many businesses on a daily basis, so you have to impress them with your offer. Now that does not necessarily mean offering the highest price.
You need to find what makes your request mutually beneficial for the rep’s celebrity client. Once you find that, make the benefit to the celeb the first information you provide. What can you offer besides payment? Maybe you can offer a chance for them to break into an audience they’re interested in but haven’t gotten into yet.
On a more basic level, make sure you keep both the subject line and the body of your email short and specific. Don’t try to get your email opened with a gimmicky headline—it’s sure to backfire.