Put all EU laws that are not to do with a single trade zone up for referendum in detail. The referendum in the early 70's did not ask people to vote on social, political or military integration, only trade. There is therefore no mandate for anything else.
Why does this idea matter?
Ever since the referendum which is the only specific mandate the British people have given to the EU, British governments have passed laws and committed to treaties based on the principal that doing so is government day to day business and therefore needs no mandate other than that at the last election they formed the new government. Most of this stuff has fundamentally altered the way we live, sometimes for the better and sometimes for the worse. However no election that I can recall had agreeing to EU treaties as a point of vote and even the Tories who are known to be Euro sceptics ended up signing the Maastricht Treaty. Given that the referendum of the 70's set the tone for how and what mandate the government was given – ie trade – all EU legislation and treaties should be subject to referendum in retrospect under the broad terms of social, political and military (trade has already been done and agreed to). The last government lied to the British people about giving us a referendum on the EU Treaty and its time we took the right to choose back by insisting on direct democracy on this issue!