I am getting $2500 for my 1425 sq ft 3 bedroom two bath Simi Home near Heywood and Sycamore built in 1964. As far as I am concerned the Kitty Letter is a waste of money. I'd have to see your property and your craigslist ad to understand why your response rate is low.
For example, years ago, I priced a rental attractively to get a "good tenant who would stay a long time and take great care of the place" because it was such an attractive deal. Instead what I got was a lot of people who were well below the standard of tenant I was looking for. When I discussed this with a seasoned property manager of more than 100 unit complexes, she asked me what going rents were and advised me to increase it to that amount, I did. Within two weeks I had received several applications from people who were well qualified to rent my unit. She explained that at the lower rental price the perception of well qualified renters was that my place might be a dump and they didnt even bother to inquire.
It does take time and I agree with Laurie that this is not an ideal time of the year for renting. Price it properly and wait for the right tenant. I have managed my own rentals for over 10 years. If you dont feel comfortable with the tenant that comes along be sure to consider what your gut tells you. I have not been burned on a single rental agreement but I am very particular. Having a Rental is not for everyone, consider that if 3 weeks is feeling like a long time to you, perhaps renting the property is not a good fit for your finances and rentals will try your patience, this may be just the beginning. However, rentals can be a great source of income. Good Luck!