Not dying your hair for a long time is a positive as there's going to be less build up on the hair. Put your hair in a carrier bag and add heat to it every 15 minutes, it won't work in cold temperatures. If you've bleached your hair, you have a higher chance of going orange.
I lived by this https://www.boots.com/en/Touch-Of-Silver-Silver-Shine-Shampoo-Weekly-Treatment-150ml_1047911/
I put it on neat, combed it through and left it on until my bath was over with and washed it out. You will get purple/silver/blue hair but it'll wash out.