For any domain you are interested in:

• PageRank - Use it as a starting point to filter and rank domains by value.
  • At least PR 1
• Newly expired domains, within the last 7 days.
• Domains that cover a specific country or region, eg .com or co.jp
• Trust flow (see below)

Use a service like expireddomains.net

All the information you need to make an informed purchase is available to you on one site.

• If the trust flow is zero, that means we cannot trust its domains and we do not use this as backlinks. 
• Any domain with less than 10 trust flow and less than 30 citation flow, indicates a domain with weak authority.
• Citation flow must at least 3 times the number of trust flow.