I follow the bed only for sleep and sex rule but my motivations are different. I generally don’t like the idea of being supine at any point in the day. It helps keep me active and productive, even on a lazy weekend.
Sounds good. Except that if I can't watch something or at least listen to something in bed. I will delay bedtime as long as possible. But if I can watch some tv series or something I usually fall asleep in 5-10min.
Don't read in bed. Don't listen to anything that requires brainpower (spoken word, for instance). Turn off the light and go to sleep. If you're not really ready to sleep, and feel the need to do a little reading, surfing, whatever, get out of bed and do it elsewhere. So I don't even bring my phone/tablet/whatever into the bedroom at all.
The idea is to program your brain to associate bed with sleep, so going to bed is a stronger cue that it's sleepytime.