You have to be very creative with the way you do this. The community of reddit is not your average consumerist who loves ads and loves to buy sh​it. However, reddit has a HUGE amount of daily traffic. If you can make it seem natural enough, and if everything is just right, it can be a great source of real traffic, and possibly conversions.
For example, if you post some cool ThinkGeek gadget on a subreddit where people post cool things, link directly to an image, but have the actual image URL redirect to a blogpost containing a review and affiliate link, there's major money to be had. Another example would be posting cloaked G2A affiliate links in gaming subs.
I recommend building up/buying an account, because people will be quick to look at your history, and you will be called out on it/reported/downvoted into the abyss.