All of this SEO stuff is good, but it takes so much time and effort to deal with. In the case of promotion, everything is pretty simple - you spend big money or big time. If you have money - just buy instagram followers on
famoid.com or order an ad on specific websites. It will work best. If you haven't money - your startup must be exceptionally good to make someone interested in. Companies hire whole teams to deal with marketing techniques. Do you think you can deal with it solo? The third option is having influential acquaintances.