Employ social media.
Every day in London there’s a different pop-up event, free giveaway, special offer, or PR event. Keeping up with what’s going on requires keeping your phone, tablet, or laptop tuned in.
Secret London (@secret_london) on Twitter has recommendations any time you need to know the cheapest cocktail bar in your area, where there’s a free comedy show, or if a restaurant is doing a giveaway.
London for Free posts daily updates and a weekly round-up of free events in London on their Facebook page. I’ve heard about everything from new phone apps to exhibitions and launch parties through them.
Also on Facebook, Handpicked London gives an overview of upcoming events. And they run satellite sites for specific areas, including Handpicked Hackney, Handpicked Brixton, and Handpicked Shoreditch.