Multiredditing is the new best thing
Multiredditing is a fantastic built-in system that lets you combine a bunch of your favorite subreddits into one steaming-hot stew of interesting posts. You can customize any multireddit you want: I, for one, combined r/pizza, r/NSFW, r/dadjokes, and r/nba, for some hilarious juxtaposition. Or, you can explore other multireddits that users around the world created.
Learn proper Reddiquette
If you want to jump in on the action and start making your own posts, it's incredibly important you adhere to the rules, general guidelines, and preferred methods that have evolved on the site over the past decade. Believe me, if you don't, people will torch you. For an extremely intense, widely accepted guide to posting, check out this post by user Raerth. It's encyclopedic, but worth a read if you value your online confidence.
Install the Enhancement Suite
Above all else, installing Reddit's Enhancement Suite is certainly the best way to get the most out of your Redditing experience. Highlights include an endlessly scrollable homepage (infinite cat GIFs!), a "night" mode to help you avoid insomnia-inducing white computer light, and the ability to seamlessly switch between different user names. Once you enhance, you'll never go back. And if you do, it's only to remember how much better off you are now. It's like visiting your ex-girlfriend, or watching the original Batman.