I try to avoid getting tan but it is sometimes hard when living in Los Angeles. I love swimming pools...so if I go to one I have my sunglasses, a big floppy hat, and sunscreen especially on the tattoos. Whenever there is a chance I sit in the shade. You could always bring one of those big umbrellas to the beach, I want to get one. It's nice to be able to have some shade.
sun is gonna fade your tattoos one way or the other, so just deal with it or bring an umbrella/sun tent or something like that. and yes, always apply sunblock, and often. you should be doing that anyway tattoos or not. as far as tattoos go, unless you go to the beach for several hours several times a week, its not gonna be a huge impact. my drivers arm is far darker than my other arm, and thats just from daily exposure in the car. colors 20 years old are still fairly bright for how old they are. i do go to the beach several times a week(to run, not to tan lol), but always in the early AM when the sun isnt at its peak, never for more than an hour. and i always apply sunblock. i know the sun is gonna do what it does, but hey thats life. i'm completely covered in tattoos, so what if a few are a little lighter than others. for some people that have a handful of tattoos it might seem like a bigger deal.
by the way, any spf above 30 is basically no more effective than 30 is.