There is some chance that BIP148 will result in an economic split of the Bitcoin currency at midnight UTC on Aug 1. If this split is non-negligible, then action may be required by all Bitcoin users. Personally, I consider it most likely that the split will be negligible and that you won't have to do anything, but it's still a good idea to prepare just in case.
A very short summary of what you need to do:
- Ensure that you have no BTC deposited with a Bitcoin bank or other trusted third-party before Aug 1. If there's no technical way for you to export the private keys for your BTC, then that BTC is at risk. Some Bitcoin banks may assure you that they'll definitely keep your BTC safe, but I absolutely wouldn't trust them.
- Do not send transactions or trust received transactions starting 12 hours before Aug 1 at midnight UTC, and continue this until you hear the "all clear" from several trustworthy sources. For example, I will post a forum news item if everything is OK, or if everything is not OK and action is required.