During a chat with IGN, Liam Cunningham, a.k.a. Ser Davos Seaworth, reveals that he hasn't yet been able to read the lines (or learn his character's fate) for next season's six-episode run because the details are very much under wraps. "I got six of [the scripts], I've got them all," Cunningham revealed, "but I can’t open them because of all the security, and I can't walk it out."
If you're curious as to how that's possible, worry no longer. According to Forbes, the scripts are not under some sort of complex padlock system that keeps them from being literally opened. Instead, they are digital copies that can only be viewed at the Thrones' Belfast studio. Until then, the actors cannot read their lines without authorization.
Forbes further reports that HBO's other alleged plan to prevent spoilers is to shoot a number of fake scenes/endings in an effort to confuse paparazzi who could potentially sneak their way onto the show's set. However, that notion was disputed by Nikolaj Coster-Waldau, better known as Jaime Lannister, who laughed it off by pointing out that that would be extremely freaking expensive and time-consuming, which does make a lot of sense. HBO will also "rigorously" enforce which international affiliates have access to their episodes.
As you might recall during season 7, HBO affiliates aired a pair of episodes prior to their release date, and hella spoilers for others were revealed after the scripts became publicly available following a hack of HBO.
Of course, you could just prevent these spoilers yourself by not succumbing to temptation and clicking on them, despite how alluring they may be at the time. In the long run, you'll thank yourself for that.