Galleries may be closed but the internet is not. Organising your own art exhibitions (whether online or when the situation permits, offline) is not just one of the most direct ways to promote your art—it also teaches useful skills in art marketing that will stick with you for life. If doing a solo sounds intimidating to you, consider putting together a group exhibition.
And it goes without saying that the more people you know, the bigger the audience you can promote your shows to; this is where #5 and #7 come in handy (on that note, another plus with group exhibitions is that fellow exhibiting artists can also put the word out to their contacts).