Permanent hair colour is designed to chemically alter the colour pigments of your hair; as such it will not wash out like semi or non-permanent colours. Successfully applying permanent hair colour without a visit to a salon is only really achievable when darkening your hair shade; if you first have to lighten your colour to change it, then seeing a professional colourist is a good idea. Set aside a good couple of hours for applying the hair colour -- you don't want to rush it.
Apply a clarifying treatment to your hair the night before you plan on colouring. This helps to rid the hair of any built-up dirt or grease and gives a fresh canvas for the colouring to work on. Follow up with a deep conditioning treatment but be sure to rinse it thoroughly.
Open the permanent hair colour kit. Most kits contain two bottles of product, gloves and an application brush. Read the instructions carefully. Combine the two bottles in the manner described in the instructions; some say to combine in a plastic container, others to squirt one into the other. Leave the product to activate for the time recommended by the colour manufacturers.
Wrap an old towel around your neck and shoulders while the colour products are activating. Comb out your hair so that it is knot-free.
Part your hair down the centre then make a second part to one side around 6 mm (1/4 inch) away from the first. Hold this section of hair up then brush on the colour mixture to the roots and the first three inches of the hair. Flip the coloured section over to the side and make another part 6 mm (1/4 inch) away from this one. Colour the roots and flip the section over onto the first. Keep parting and colouring the roots in this manner. Once one side is done, flip it all over and do the other side and the back in the same way.
Leave for around 20 minutes or however long the instructions stipulate. In this time wipe off any colour that may have come into contact with the skin around your hairline with a cotton swab.
Apply the remaining colour to the mid section and ends of the hair then comb your hair to ensure the colour is uniformly distributed. Leave for a further 5 minutes then rinse the hair thoroughly so that the water runs clear. Apply a conditioner and leave for two or three minutes then again rinse thoroughly. Dry and style as usual.
Check the colour on a couple of strands of your hair before applying to the whole head.
Some hair colours can cause irritation. If you have sensitive skin, apply a small amount of the colour to an inconspicuous area of skin and leave for ten minutes. If a reaction occurs do not use the colour on your hair. Do not shampoo for 24 hours after colouring.