Hey...
Let me start the answer with a question.
Does being a Christian mean that your life is Joyless, boring and uninteresting? If you ask a genuine Christian, they'd never accept it! Because Joy is one of the main characteristics of a Christian's life - a joy of a much greater measure - a joy that comes from knowing Jesus and enjoying Him.
Now coming to the question of entertainment, we aren't told that our lives should be devoid of entertainment. So how do we go about it - in a balanced and non-sinful manner?
1. Abstain from what is definitely sinful
Some shows, movies, music etc are directly in conflict with the Bible. The content is harmful and promotes wrong thinking, actions, behaviour in us. These are things we should abstain from no matter what. Some eg: Music with bad or negative lyrics, Movies with lots of violence or sexual scenes etc..
2. Content which are potentially Addictive
There are serials, games etc which are designed to be addictive and lures us into it, eventually robbing us of a lot of precious time. You can definitely try to put some check points to make sure you are not over indulged in it, but again if you see that is not helping - quit it. As a Christian we should be wise enough to recognise and avoid harmful things from becoming a part of our lives. It's always good to NOT run unnecessary risks.
3. Priorities matter
Sometimes, the content isn't harmful or necessarily bad, but there are other more important matters that requires our attention. In this case, we should go with the right priorities instead of skipping important matters to relax.

Also, another helpful thing to do is to check, what is what I am watching/playing/listening doing to me? Are others pointing out some bad changes in me recently? Are those bad changes a result of something I am watching or listening to? These are good helpful questions to ask.

Healthy entertainment is helpful - for eg: Watching a show together with your family or siblings, if it gives a good quality time together, is a good thing to do. Whatever we do, we should be wise in testing what we consume and how much we consume those things that affect our mind. (Phil 4:8)
Do check out the recommended resources for some really good things to keep in mind when it comes entertainment.