I would look online for similar lines and see who their reps are. Then send the rep groups samples of your product for them to try. It also helps to have statistics. For example when I started my company I had a store that sold about 8 cases their first month. I gave them that info as well as the store owners name to verify that the information was in fact true. Reps want to know that your product retails. I am also always open to help. i got my start here and my company did over 1 million in sales in the first year. Its time for me to give back :) Good luck!
Great advice is to look for similar lines. And it IS hard to get your first rep, it took us 6 month to find her. But after that, once you mention that you have sales reps and showroom(s) it is a completely new game. Good luck!
I remember when I was asking myself same question 3 years ago. I wish there were all of the resources available today to avoid mistakes and wasting your time. I`ve recently found a great website and they have an article that will answer your questions: Fashion Business World. I`m not sure if link would work, you can just go to www.fashionbusinessworld.com. Hope this helps.