Well first off, it costs about 5 times more to get a new customer than it does to keep an existing customer. Before advertising for new customers, you really have to take care of your current clientele. Spending money on advertising for new customers while you don’t have a good system in place to keep them is pointless. You want to keep your existing customers happy, which will make them want to come back over and over again. You must build relationships with your customers and provide great customer service by keeping in touch with them by phone, e-mail or whatever.
I would suggest talking to your current customers and have them fill out a little survey or something and offer a chance to win a free detail. These customers will be able to tell you a lot about your potential customers. Ask them where they buy their newspaper, what roads they travel on, where they shop, where they spend their weekends, etc.. This will give you a better idea how to reach your target market.
Word of mouth is the by far, the best and cheapest form of advertising. You should offer some sort of VIP/referral program to your current customers. Print up a bunch of business card coupons. On the front of the card, write your special offering. On the back of the card, put "referred by" and leave a blank space for the your customer to put his name, number and e-mail address. Every time a customer comes in, hand them some new ones. Tell them to fill out the cards and pass them out to family, friends and co-workers. If their relative, friend or co-worker uses the coupon, they’ll get a special discount on their next detail. You will need to keep track of this on a spreadsheet.
Another great way to grow your business is cross-promotion. Work with body shops, auto repair shops and dealerships and have them hand out your fliers to their customers to promote your business. Do the same for them in return, but make sure you are referring your customers to someone that is reputable.
If you decide to make up some cards of flyers, your biggest goal should be to get your customers to buy now. Offer some sort of discount or free offer with the purchase of a specific package. To promote your offering, make sure to include an expiration date on the card or flyer which will give the customer a deadline. If you offering them this great deal, than you will have to set some sort of time limit to get the customer to act on it. If your offer expires in 1 week, they can't wait until "someday" to come in.
Sorry this is getting lengthy, but just remember to always take care of your existing customers. Follow up every detail with a follow up call or e-mail asking the customer if they were satisfied with the work you performed. If a customer is not totally satisfied and you do not fix the problem, they are going to tell people they know and never come back. If they were not satisfied at first and you fix the problem, they will tell others how good they were treated and refer others. The goal is to keep a customer for life. There's no point in spending all of your money on getting new customers if you can't keep your current ones.
Hope this helped....
~Rick