First off, know your audience. Craft your content in a way that'll resonate with them. Use graphics that pop and write captions that hook people in. That'll make 'em want to check out your Soundcloud profile.
Join communities where your fans hang out. Make the most out of hashtags to broaden your reach and find folks who are into the same stuff as you. Team up with other artists and influencers to grow your network and reach fresh audiences.
Above all, keep the engagement going. Be active!