How do i escape Silver 3?

I finished my placements like a week ago and got placed s3. I was happy. I played five of those games with my G1 premade. Then i kept playing with him and got to my promos, which i lost. And now he's gone for a month and as soon as he left my lp started dropping. I prefered having higher mmr players on my team and people that don't get caught out as often, and that have a better vision score. I main mid/supp, sometimes i go supp/mid. My midlaners are Lisssandra , Cassiopeia , Vladimir , and Ahri . My support pool contains of: Karma , Zyra , Morgana (even tho i don't like playing her much) and Sona . The only champ that i haven't played in ranked is currently Sona. I plan on buying Janna , Thresh or Nami .

P.S. This is my first season of ranked. I understand that i got to my promos only once, and that i shouldn't expect to climb incredibly fast. If i'm complaining a lot for my first promos, just tell me that it's completely normal for my lp to drop like this, please don't go full hard on me.