I think spaying and neutering will help quite a bit! Usually the sooner you get it done, the better, and less chance of them starting the 'bad' behavior
I have always had my males neutered at about 6 months, if not sooner.
I have not had a female for awhile, but I know Liza (RB) was spayed at UNDER a year...........maybe 7-9 months. I don't remember exactily.