I've ranted time and time before about this, and got the idea that I should make a guide thread about it.
Why is serious roleplay interesting, and why does it have to be so serious? Why do things have to make sense, why are plot holes bad and why is it bad when people only roleplay to 'win'? Here is why.
A good serious roleplay is like writing a good story or screenplay with a bunch of other peoples. Making it interesting to roleplay in is just like letting people get interested in your movie or fantasy novel. The characters have to be easy to relate to, interesting, the plot has to be interesting, and can't have plot holes, nobody will want to pay attention anymore if you want to suddenly bring in rifles to a fantasy roleplay.
It's important to make sure your character's actions make sense, sure, but it's much, much more important to get the right character involved at the right time.
Do you plan on getting something from the forest? Don't speculate on how you are tougher than a bear, speak to characters who are mercenaries for their career. Want something built? You are not a Canadian handyman, just talk to someone who builds stuff. Do you have something that someone needs? Man up and ask to assist.
Being serious is important, but if any goofiness or strange things happen then it should be because that's what the character(s) would do in that situation.
If a character does something aggressive or stupid, that hardly means that the roleplayer isn't as good at roleplaying at you, most of the time it means that's what the acting character would actually do in real life.
Not everyone is an extreme pacifist who speaks like a teenager or perfectly clear, and if a roleplay setting was real life, chances are it wouldn't have the same social norm that real life has.