1. Make sure the traffic is quality. Referral traffic from Reddit isn't repeat traffic. Traffic from PPC isn't repeat traffic. Percentage of return visitors and a high percentage of visitors coming from search engines or from permanent referral links are valuable.
2. Make sure the income streams can be easily swapped to the buyer. For example, a PayPal product requires just replacing an e-mail (in the old days), but I think nowadays requires replacing a Client ID, which is a little more involved but still straightforward. Likewise, for Google Ads, assuming both buyer and seller already have an approved Google Ads account, it's a straightforward process of swapping out the old publisher's ad code with the new publisher's ad code.
3. Once traffic and revenue are sorted, make it easy and trustworthy for buyers to buy from you. For example, accepting Escrow.com as a payment method smooths the transaction process immensely.