This is a tough one to answer, cos it depends on where you’re at in your journey.
Do you already have an active and supportive community on a platform or multiple platforms? If so, your best bet is to activate them to be a part of the experience of getting your album out there, cos they want it as much as you do! Basically, turn your most enthusiastic ‘fans’ into your street team, asking them to share, promote, email, put up posters, etc. Research ‘street teams’ to learn more about this approach.
If you don’t have any kind of following, or not one that’s very engaged with your journey, then I would look into Facebook ads. Create highly engaging videos (the most visible content on Facebook these days), lyric videos, funny videos, etc, and get them moving by paying for some highly targeted ads.
This is not an area I have overmuch experience in, as my releases have all been very small-scale, and I have a small though passionate tribe which loves to support my art.
As with all of this, each situation is unique, and it’s up to you to be courageously creative in finding solutions to your particular challenges.
I wish you well on the journey