I would not tell you to not do any of these things. But... if you live by the search, you will die by the search. Unless you are one of the big sellers, you are not going to come up very high in the search, with the rare exception of course. That is just a fact of life.
I personally don't see any correlation what so ever between sales and belonging to groups and being in contests. None. I have sold images with zero likes, votes, features, contest wins, comments and with few keywords and no description.
Yesterday I sold two images. Neither one of them have ever been featured, been in a group or entered into a contest. Neither one has even one like or vote or comment. They have never been FBed or Twittered through FAA. I have advertised both directly on FB and Twitter.
If want to sell, you get your links seen OUTSIDE FAA. Promote specific items with links that take people to those items on your ArtistsWebsite.
Use any method you can to get seen outside FAA. The quick, easy and fee methods include Facebook, Twitter and the other Social Media. But I would pick one or two and concentrate there. I don't think you can use them all. I believe in then old adage of Tell'em, tell'em what you told'en and then tell'em again. If you try to use too many SB outlets, that will be come a lot of work real fast.
I would also consider email campaigns, banner ads, link exchanges, press releases, pay for clicks, and any other form of online advertising.
Some people use blogging but I have tried to stay away from that because then you have to promote your blog and try to get it seen. However, I would suggest you check into writing articles for the free article distribution sites that are out there. That way you don't have to find the readers, they do it for you. If you do write articles, then I would go ahead and start a blog but I would not spend a lot of time promoting it. Also remember that when you write articles, they will be picked up more often and stay in place longer if they are not time dated.
Then of course there is promoting to your local market through art shows, business cards, flyers etc, etc. Any where you can get your name seen. Make sure you promote your ArtistWebsite and not the FAA site. Once they enter your AW, you have a captive audience for only your images. Once they enter the FAA site they now have access to 7 million images.