3. Cast A Star Who Was Popular Ten Years Ago
What The Studios Think: In reality the special effects are the star (see point 5), but as you need to give the semblance of something relatable you'll need to bring in some real humans too. An up and comer is a good idea - Star Wars did perfectly OK with Mark Hamill - but somewhere in the cast you need a big name to whack on the marquee. A name of someone that not just those up to date will recognise. Someone whos been around a good long while.
Pro Tip: Cast Will Smith or Tom Cruise. That way, you can spend ages in interviews talking about how you've got the biggest actor of all time, making you look particularly out of touch, not to mention stopping you moving being called anything other than The New Will Smith/Tom Cruise Movie.
Why It Doesn't Work: Nineties nostalgia has meant some actors still carry a great deal of respect despite not having done anything new recently. The two I named there periodically appear in films of a similar style to their earlier hits bringing little new the role. It gives films often aimed heavily at young people an appeal to an older demographic, but its a tried and tested trick many are now wise to.