I’ve heard good things about Vault, but I haven’t tried it myself. It looks fairly technical, but very versatile and local. Encrypting your entire hard drive would probably be easier, but Vault gives you more control and more options.
For an easier but cloud-based solution, Keybase has very easy to use encryption. You just install it and drop your files into the Keybase file system, and everything is magically encrypted. It’s like Dropbox but with end-to-end encryption built in, and it makes it easy to control your own keys so you can be sure that no one is snooping on your files. Sadly though, I’m not sure there’s a way to use it without the cloud features.