Hi there. In my experience, the more sites you make your content visible through, the better. I'm not extremely famous yet, but I have a fair amount of subs via YouTube, and at least 1/4 as many followers on Tumblr. I find a few Tumblr features particularly useful:
-reposting is easy so people who like your posts & "repost" them is like free exposure/advertising.
-So you don't post too much all at once, you can use the "schedule" or "queue" feature and queue up to 300 posts to be released once a day or up to 10x/day. Once every so often I'll compile a bunch of posts in the queue and then even if I'm not active for the next 6 months or so, it appears like I am, lol.
-When creating your tumblr post, you have the option to automatically share it to your facebook page or profile
-You can also use an outside service such as ifttt.com or hootsuite where if you post something on for example instagram, then it'll automatically post on tumblr / facebook / twitter.
Hope those are some helpful tips
-Jenni
PS: also, if this kind of stuff doesn't totally bore you, it may actually be kind of a fun hobby, I like the customization & layout options on Tumblr