I think that the hardest part of the direct sales business is the sales and marketing aspects. Since you do not have a store location you cannot rely on foot traffic and have to generate interest in your product line in other ways.
A lot of direct sales opportunities explain that one of the best methods of marketing to the public is my inviting friends and acquaintances to come to a party so that you can demonstrate the products for them.
While the first party might be easy to set up the subsequent ones require more work. A lot of these companies will allow you to offer an incentive for someone else to host a party and they would get free products. This is a word of mouth type of marketing method that relies a lot on referrals and repeat business.