According to UASF Working Group
What do users need to do to enforce BIP148?
It is recommended that users do not update unless an economic majority commits to updating and users are aware of the risks and mitigations of a failed UASF deployment.
Users aware of the risks and who want to commit should use clients that enforce BIP148. Users that run full nodes would upgrade to one that enforces BIP148, or run their node behind an upgraded border node. Users of light clients (like mobile wallets) should check with each vendor to see their support for BIP148. We plan on documenting any public responses from wallets regarding BIP148 support.
This web-page describes the mechanism for any User Activated Soft Fork (UASF)