First off, great question.

I'm still on my first Hogwarts charrie, but I have an interesting story with her. I got her sorted and all set up when I was still new to the site, and posted her going on the train ride to Hogwarts. After being too new to the site and not knowledgeable enough with how RPing worked, I simply did not post a single other post with her. So, a couple terms later, I decided to play her as a first year. It was successful, and she is a third year now. So basically...

a) Yes and no. I gave up, but I didn't give up my character. I simply restarted her.

b) I think that a great way to really get involved and not give up your character is to connect with other SSers. Honestly, one of the reasons I tried again was to get to know people on this site. I am good friends with the people who play my characters friends (and enemies), and that helps a lot with motivation. Another way is to just play around, especially in Diagon Alley. This just serves as a base for trying new characters out. Lastly, just post! Get involved in a Potions class, do the Herbology homework, et cetera. It helps so much.