I don't know if this applies to all shaders, but at least some of them require you to... Read All Wow, shaders really make Minecraft beautiful! If you haven't tried them, you're missing out. I've embedded a video that shows off some different ones. Beware that some shaders may require high-end hardware, but there are also some for low-end hardware, too (check out https://youtu.be/swOAdaTN770). You may want to look for information on the web about the various settings in each shader, some shaders have different presets you can use, which don't require you to change any settings. Otherwise, just play around with the different settings and see what looks and performs best for you.
I don't know if this applies to all shaders, but at least some of them require you to install Optifine. If you're running Minecraft on a computer, you should be using Optifine anyway. It comes with a lot of features that help the game look and perform better. Optifine doesn't work with snapshots, so if you want to try it out, you'll have to check Optifine's versions to see which Minecraft versions are compatible. You can check it out at https://optifine.net/downloads. Installation is easy. Download whatever version and wait for the "skip" option to appear in the top right side of the page (if you're using an Adblocker, you won't see an ad, just a banner). You'll download a .jar file, which requires that you have Java installed. Once all that's done, double click on the Optifine file and click "install" and it'll be installed quickly. You'll need to select the Optifine profile next to the "Play" button on the Launcher. Then, when in Minecraft, go to your video settings and check out all the options.
I decided to check out Sildur's Vibrant Shaders and it makes Minecraft look amazing! One quick tip I have for you is to turn off Vsync. I usually have Vsync on, because I don't like screen tearing, but I don't notice it in Minecraft unless I'm move the mouse really fast to see if I can see any screen tearing. Turning off Vsync will unlock your FPS potential, instead of limiting it. With the setting on, I was able to get 60 FPS (for my 60hz monitor), but it averaged about 40-50FPS sometimes, which I think is still playable. I turned Vsync off and now I'm seeing an average of abut 100 FPS.
Have you tried it out? Do you have a favorite shader pack? Are you using Optifinet? Feel free to let me know. If you want help, I can try to do that, too.