Depends on the group.

Serious riders, casual ride: You may accelerate slowly when you get to the front if you like, and the group may accept it, or they may not. Slow up a bit and hang out for a bit. Maybe you can take off and have some fun, but come back to the group in short time.

Serious riders, serious ride: Don't drop people, but go ahead and try to gradually push the pace. Most likely you can hammer hard up the hills and people will follow.

Serious riders, drop ride/race ride: Hide when you are tired, attack the group when they are tired. Try to win.

Casual riders, casual ride: Pretend you are sightseeing with your grandmother.

Casual riders, serious ride: Take your pulls, but be careful. These will likely be steady, aerobic pulls - not hard pulls. Try not to accidentally drop people. It can be good practice setting pace for weaker or slower riders. In these rides, I like to see how fast I can get everyone going without dropping anyone. Pay attention to how others pull as well: how hard do they want to hit short hills/rollers? And it's strange, but sometimes you have to reduce effort for longer, slight grades (1-2%): a slight grade will reduce speed/draft, so others have a harder time following.