Hair advice

So my hair is naturally blonde but I decided to color it red two months ago and now I'm wanting to be blond again. I used ion hair color with a 10 volume developer. I have stripped my hair twice in the last two weeks and have done a hair mask every night. Does anyone know any tips on how to minimize damage while bleaching your hair? I can buy professional products because I am a cosmetology student. I asked my instructor if she thought my hair could take it and she said yes. Also is there anything I can put on my roots to prevent them from being bleached? Like petroleum jelly or something it cant penetrate? Also what would you recommend to take out brassy colors?