How can I keep up my average in this cl?

I'm a sopre in Honors cles, and I get good grades =] The History and English programs at my high school are extremely difficult, and I got my first "C" ever the first quarter this year ! However, I tried very hard to improve my theses and to receive better grades on tests this past term, and on my report card today I went up to an "A-" =] Now, including my midterm grade, my average is a "B" which I would like to maintain! If you have any ideas on how to keep my average up, please let me know! Thanks =] ♥