Using too much hairdye can cause long term damage to your hair, so it's probably best to seek professional advice before you go making any serious changes.
You should select colour-safe shampoos and other products which are designed specifically to protect dyed hair.
It's also a good idea to apply swimming conditioner to you hair after moistening it to protect it from harmful chemicals, chlorine, or salt from the ocean.
If you're tying your hair back never use raw rubber bands as coloured hair is weakened and more prone to breakage. Use a bristle brush to brush your hair.
Daily hair conditioning is essential for taking good care of your hair, as dyed hair is drier and more brittle it'll need that extra moisture.
What a lot of people don't know is that after you colour your hair, you should wait a few days before shampooing to let the colour be completely absorbed. If showering, just use conditioner instead of shampoo in order to keep the hair damp and the colours fresh.
A big no-no is the use of a sunbed as well as excessive exposure to sunlight, so if you have to go outdoors on a bright day, cover up!