My last release I went thru discmakers, which auto releases it onto just about every streaming site. Convenient, but not necessarily what I'll do again.
For artwork I just take a good photo of something tied to me or my music and have a graphic designer friend of mine get my band logo and other necessary information on there. He wouldn't accept credit or money for it so I am fortunate in that regard.
I'd recommend sending it to as many radio stations and radio shows as will accept unsolicited releases, that usually means scouring NPR for shows tied to your genre, otherwise your spotify, apple, etc won't get any real plays since unless you are getting some dj spins and gigging you aren't creating a market. That means sending a couple hundred emails out with your music in WAV or MP3, contact info, one sheet/band bio in pdf form, and any links to website and social media. Some of the old school places are still gonna want a hard copy of your music so printing a 100 CD's might come in handy, or it might just fill your closet. I highly suggest creating a template on gmail for that so you can blast them off quickly. I sent out a few hundred emails with all that and have about 30 monthly listeners on my spotify....not exactly worth bragging about but it was a start and now I have contacts I can get in touch with without going through all that again for the next release.
There are also the critics, review rags, and other media you will want to get your release out to in order to build interest. Some of them want money, some of them don't. Most of them do a half assed job, some of them do a half assed job and then offer to advertise it on their rag for money. Usually there is a backlog, so months later your review will come through...unless you buy adspace which in many cases will move you to the front of the line.
If you really want to blow some dough then find a publicist with connections to XM and other bigger station markets that can get you on there with a phone call, otherwise it's a door you can hammer on forever and never get in. That'll run you $600-1200+ per month. And people still mostly will never have heard of you, especially if you aren't gigging.
Good luck.
