The most important thing you can do is perform your own network consensus by running a full-node and creating and storing your own private keys.
This means you will need to run a full-node for the legacy chain, likely Bitcoin Core, and a full-node for the BIP 148 chain, likely a fork of Bitcoin Core with the BIP 148 rules enforced.
This will put you in firm control of all decisions related to how you interact instead of having some third-party make those decisions for you.
Additionally, it is unknown how the legacy chain or the BIP 148 chain will be labeled.
This could lead to significant confusion in the marketplace so it is important for you to know exactly what you are buying or selling.
Possible scenarios from BIP 148
BIP148 requires support from the economic majority, particularly exchanges and wallets. If this does not occur, node software supporting BIP148 should not be run after August 1st as it will cause a chain split leading to the abandonment of BIP148.
There are strong economic incentives in the Bitcoin system for nodes to cooperate and remain in consensus to prevent chain splits. If the economic majority is signalling as of August 1st, miners have many incentives to follow along.
Not following along would make it difficult to sell coins mined after August 1st as the blocks would not be accepted by the economic majority. Essentially, miners would be producing an altcoin not recognized by users and exchanges, making them less useful and in lower demand.
Some miners could opt to ignore the BIP148 rule and attempt to split the chain, but this would require a majority of miners who would be out of consensus from the rest of the economic majority.
If a majority of hash power follows BIP148, all nodes will follow the chain regardless of if they are running BIP148. Non-compliant blocks will be orphaned. All SegWit nodes will eventually activate SegWit.
If a minority of the hash power (under 51%) follows BIP148, nodes running BIP148 will be fine, but those not running BIP148 will be out of consensus with the rest of the economy. In this scenario, the more of the economy that runs BIP148, the better.
Miners will find it difficult to sell their coins leading economically motivated miners to start enforcing BIP148.