The primary mitigation tools are a pre-filing trademark search, adjusting the mark or classes based on what the search finds, and engaging directly with the owners of potentially conflicting marks before filing.
A professional trademark search covers not just identical marks but phonetically and visually similar ones in the same and related classes. If the search identifies a high-risk conflict, adjusting the mark to increase distance or narrowing the classes to remove the overlap removes the basis for that opposition before it can arise.
Where a potentially conflicting mark exists but the commercial contexts are different, approaching the earlier owner for a co-existence agreement or consent before filing can prevent an opposition from being filed even if the marks are similar.
A free trademark search with Trama can identify conflicting marks before you file.