Follow tags first and foremost, there is a feed that shows just a tags feed (order your dashboard in chronological order). Then follow people that post things you like in the tags. There are no influencers on tumblr so don’t be afraid to send people asks/messages.
Also, remember to change your icon and add a description to your blog so people know you are not a bot.
Feel free to ask me questions either here or on tumblr, and welcome to the Hellsite (affectionate)!