My hair is in superb condition because I colour it myself. Hairdressers strip the colour out before putting colour back in. It is easy to do at home yourself and far gentler.
You need an old towel and everything else comes in the pack. Just mix the product according to instructions, shampoo on, wait the required time then wash off until the water is clear. Squeeze excess water out of hair and apply provided conditioner, comb it through (I leave it on as long as possible) rinse off then style as normal.
Don't worry if you get dribbles on your face or shoulders, just wipe off with toilet paper. Don't get dribbles on carpets or clothing ( I do it naked and remove bath mats, towels etc from the bathroom). While waiting I sit on the toilet reading Gransnet (sorry TMI) or listen to Einaudi on YouTube.
I sometimes use half a pack to do my roots combing it halfway through. Whole pack costs around £7 so I save a fortune but it looks so much more natural.
I use Preference by L'Oreal but believe all the big brands are similar.