Facebook – You should definitely join Facebook because they have over 1 BILLION active users on average each month (as of 2014). Make sure you setup a Facebook Artist page and join as many Facebook Groups as you can too.
Twitter – Definitely join Twitter, they have 255 million monthly active users with about 500 million Tweets sent daily. Send out quality tweets as often as you can and take advantage of hashtags.
Instagram – Instagram has grown tremendously over the years and have over 200 million users. There are apps you can use to promote snippets of your music.
YouTube – Has over 1 BILLION users. Make sure you start up your own channel and upload videos of your music.
Google Plus – Google Plus has over 1 BILLION users and it is considered competition to Facebook.
LinkedIn – Great site for networking with others in the music industry.
Tumblr – This is a great tool for simple blogging and sharing of your music.
Soundcloud – This is a very popular music website that allows fans to comment, like and repost your music. You can easily embed & share songs too.
AudioMack – This site has stepped up their game in recent years and its a must have to promote your music.
Reverbnation – This site will help you gain new fans, find collaborations and help you get discovered.
Bandcamp – Is a great site to promote your music, gain new fans, get discovered and raise funds.
DatPiff – If you are into making Hip Hop music or beat making then you definitely want to post your mixtapes here.
Beatport – If you fall into the DJ or electronic music genre, this is a great site to promote your music or mixes.
Artists.MTV – Set up your page on MTV for free.
MyFlashStore – Similar to Beatstars with their own marketplace.
CDBaby – Easy way to publish & sell your music on iTunes, Google Play, Rhapsody and Amazon MP3.
ASCAP – Site that protects your copyrights to your songs, collects and pays you royalties etc. Cost is one-time fee of $50.
BMI – Same as ASCAP except it’s free for songwriters, $250 to sign up as a publisher.
SESAC – Same as ASCAP but based out of Europe. Membership is invite only.
Dropbox – Very handy for sending music demos and samples.
HulkShare – another easy way to send music files and also embed music
GoFundMe – This is a crowd funding site and can help you raise funds fast.
MailChimp – Great way for your fans to join your email list.
FanBridge – Similar to MailChimp for email marketing.
Paypal – Great way to receive and send money online. A lot of artists use this to get paid for features or buy beats, etc.