You can increase your boutique's sales by forming joint ventures with other retailers. 

A joint venture is an agreement between two or more businesses in which they come together to form a mutually beneficial partnership. 

To put it simply, a joint venture is an arrangement that helps two or more businesses make more money by working together. 

For example, if you have a handbag boutique, and your friend has a dress boutique, you can make an arrangement in which you refer customers to each other. 

At your boutique you can give out coupons for your friend's boutique, as well as display an advertisement on your store's wall for her boutique. Your friend would also give out coupons for your boutique, as well as have an advertisement on her store's wall for your boutique.

Another joint venture strategy is to split the cost of an advertisement. 

Let's say you wanted to advertise your shop by taking out an ad in the Wall Street Journal. The cost of the ad might be too high, so you might want to split the cost of the ad with another retailer. 

You and your fellow retailer would benefit from the exposure that an advertisement in a national publication can bring. 

The best retail joint ventures are those that consist of shops that serve the same customer categories. Most likely, a women's suit store and a women's dress store, both serve the same customer categories. 

Remember, business is based on trust, so make sure that you are forming joint ventures with retailers that you feel comfortable with, and who you can trust.