Step 1. Learn to use the site without worrying about your videos.
Reddit seems confusing because it is like 1000 forums all posting at the same time.
look for subreddits that relate to your content and favorite them. Look for anything in the world that you like or do as a hobby and there will be a community on there.
Join them and comment on the posts and put up your own (just like here).
This is to build up your account and to show you are not a lazy spammer.
Step 2. Once you have built up your account and are ready to do a little LIGHT promoting (do not spam as you WILL be banned or your YT page attacked with dislikes). Do not post in huge threads like r/videos as your content will be drowned out. Try to really find a niche forum that suits your video. Make sure it is large enough to have people look at your stuff (a forum with only 100 users is not going to help you).
For e.g my newest video is comedy, but specifically it contains a TV commercial. Even more specific the video is me ripping on how crap the commercial is.
I legit found a forum (or board) r/bullshitadvertising with 2100 users.
My video will stay on its front page for a while because not all users submit. But all users that log on that day or day after will see my video in there feeds (front page of reddit).
Step 3. Dont go on a spamming spree - put your video in 1 thread then continue using the site and commenting and uploading on topics you like. If you dont get any traction wait a few days and try another subreddit (but between those days keep commenting on other things)
Basically this site right here YTtalk works on the same principle as reddit.
You just cant come in and post your video across multiple threads then leave and expect them to stay up.
You have to participate in conversation ect...
The main difference is the users of reddit are a wide spectrum. some supportive, some trolls, some very aggressive in hating things.
I never EVER explicitly make it known in any post that the content is my own, this helps dodge haters and trolls to a certain extent.
ALSO:: this will not get you instant fame. Just like youtube what takes off and what falls flat is a mystery. I have gained big increases form there on some videos and others I feel are more polished or funnier have literally done squat.
hope that helps - enjoy.