Building a business could be easy, but building a business focusing on success with a robust foundation could take consistent efforts and effective strategies. Key sales strategies that can shield a direct selling business from unforeseen challenges and economic adversity are those that can ensure success in the journey of a business.

1. Strong customer relationships - to ensure every customer is considered and given the best of services through an efficient Customer Relationship Management (CRM) platform. 

2. Offer value to customers - as much a brand takes effort to initiate customer relationships, it is important to retain them as well. Loyalty Management Software could help businesses build customer loyalty strong enough to build the trustworthiness and reliability of the brand.

3. Social proofing - social is the space where everything is transparent. Customers could leverage your social presence to share their ideas, suggestions, and reviews about your brand and the product. 

4. Product education - educate your customers first before you sell something to them. The more they are aware, the more it is possible to get sold and promoted among their friends and peers. 

5. Customer referrals - encouraging customer referrals is a great way to ensure that your brand is promoted effectively through word of mouth which is a powerful marketing weapon. From lead generation to social media sharing, customer referrals could be helpful with customer acquisition and retention in the long run. 

Putting together these key factors could help direct selling businesses navigate faster toward success with a robust marketing foundation. In an unforeseen circumstance where the brand has a shortcoming, it is easier to get over it with these strategies effectively set in place.