As the coil accumulates a gunk buildup from flavoring, it is less efficient, so more juice that wicks up to it doesn't get vaporized. The flavor gets muted too. You can try a good hot water rinse, and a more advanced approach is to learn how to "dry burn" the coil to turn that buildup to ash which you can wash out.
You can search here on ECF or on youtube to learn how to dry burn eventually, extending the life of your coil and clearomizer. As you just got started, it might be a good idea to get a couple extra clearomizers and just replace them to keep vaping simple. You can also get clearomizers with replaceable heads, to keep your costs down.
Many here will tell you that clearomizers are for starting out or aren't very good, but they are the most commonly used way to vape at this point. If you are vaping to stop smoking, they work fine. If you want to make more of a hobby of vaping, you can always get a wide variety of devices to try different techniques. Good luck and keep on vaping!