Colouring your hair every four to six weeks depending on the type of colour you need, if its a full tint to cover grey roots then you will find yourself in the salon allot more often. To extend your salon visit us a root touch up product they are great for giving you an extra week or two before your colour is due.
Less is always best when it comes to colour, try to find a salon that uses products with less chemicals, your hair will thank you for it, darker colours tend to have more chemicals so if you can go lighter that is a better option.
All permanent hair colour have some level of chemicals the best ones on the market only use a very small amount, adding lots of organic ingredients to help your hair maintain its natural shine and strength.
Even if you dye your hair at home take a visit to a local health food shop they will have home hair dyes with less chemicals they are more expensive but worth paying the difference in the long run.
Many salons are using better styling and colouring products with far less chemicals. Finding the right salon to suit your needs might take a few visits but if you consider how often you are colouring your hair then its best to stay with a salon who decide to use a brand that is gentle but effective.