A young child who may not go to bed right away at bedtime can get better at this if you practice a bit. This can be pretend practice during the middle of the day. Set it up as a game. He goes to his room and gets into bed, pretending it's bedtime. You praise all of that. Practicing this a few times in a given week will increase the likelihood that he goes to bed better at bedtime—and be sure to praise that, too.
Practicing the behavior in pretend situations is still practice and still builds the behavior. Remember, commercial airline pilots practice all of the time in "pretend" situations (called simulators), and that practice carries over to real situations. Boxers practice and train in the gym to develop habits they will call upon on fight night. It's the same with behaviors you want to develop in the home.
5. Shape the desired behavior by rewarding gradual approximations of it. If the behavior does not yet occur the way you want it—not a full hour of bassoon practice, not a full hour of homework each day—praise lesser durations and partial successes and build them up over time.
The use of praise to develop behavior in the way we've been describing it is systematic, temporary, and a purposeful addition to—but not a substitute for—the ordinary warm attention you normally give to your children just because you love them. Why not test it out for a brief period? Let's say three days. For three days, try to use praise as a reward in the ways outlined above. You should see a difference in your child's behavior and in the emotional climate of your household.
Praise is one in the larger set of positive experiences that builds the relationship between a parent and child. Many parents and others in authority rely instead on threats, hitting, and punishment more generally, especially when trying to teach respect. More punishment leads to children escaping and avoiding the punisher; more effective praise makes for closeness and better relationships. Because praise for positive behaviors decreases the need for punishment, it helps to make a family closer and warmer. In seeking to strike the balance between them, the rule of thumb when trying to change behavior is that praise for good behavior should be much more frequent than punishment for the behavior you want to eliminate.
None of this looks anything like bribery. Rewards tend to become bribery when they're unsystematic, unconnected to clear parental expectations, and used to try to get your kids to do things at odds with the model you provide with your own behavior.