First we will update Minecraft to 1.12.2, Open your Launcher, go to "Launcher Options" -> Add New -> choose version 1.12.2.
Step 2: Download and install Optifine HD
Download Optifine HD, and run the installer, click on install and wait, after a few seconds the optifine will be installed.
I recommend that you read this mod review about optifine.
Step 3: Opening Minecraft with Optifine
Open your Minecraft Launcher, choose the Optifine HD profile to start, and click Play.
Step 4: Installing the Shaders Packs
With Minecraft open go to OPTIONS-> VIDEO SETTINGS-> SHADERS inside the Shaders window click on Shaders Folder, this is where you should put all the shaders packs you want, you can download shader packs here.
Step 6: Conclusion
If you have followed all the steps of this tutorial properly, your minecraft is ready, remembering that shaders and textures require a computer with good settings, if you have a lot of lag, see a tutorial on how to remove minecraft lag using optifine.