In Advanced search use the relevant filters to find the target Companies or Contacts you desire.

To save the results, use the +Add To List button and give the List a name.

Tip: The List will be saved as a Company or Contact List based on the tab you're viewing when you save the List. ie if you're viewing the Company tab and click +Add to List, it will be saved as a Company List. The same applies for Contact Lists.

When it's time to revisit your List, you can find it under the Lists tab in the blue ribbon at the top of the screen. Alternatively, you can start a new search and find your Lists using the Lists filter.