I got to Diamond, solo. The advice above is mostly solid. I'd like to add my two cents for verification:
1. Do not care about your team: If you can play well solo, they can play well as a duo. Maybe they'll be with you to the end, if not you'll be carrying them (they should be thankful for your ruthlessness). Absolutely do NOT bake yourself trying to rescue angry, pinging team mates who got themselves killed while a full team hovers about.
2. Do not fear the ring, the ring is your friend: Learn to fight in the ring, you will also even get some good vulture kills from people not expecting others in the ring (and consequently, do not let your own guard down). You have a long time with rings...2 full ring rounds where you can easily sustain and pretty much through round 3.
3. Gold armor is good armor: Yes, raising your purple to red is better in general, but the heals of gold in shields and health can keep you living in both the ring, and if you have to run. And, yeah, it's still just fine.
4. The Gold Knockdown Shield Sucks...but it is good for you: So important when your buddies get themselves smoked. It still is dumb in how long it takes you to get up again, but it might carry you through those last placements if you can.
5. Pick the right characters: Respawn boned this one, but obviously certain characters are better alone and some are better with a team. You are a solo mofo, so pick a character accordingly.
6. As has been said, don't drop dumb: Decouple yourself immediately, you can always follow your team. But it let's them know you're not playing stupid right away, and you can ping where you want to go (and then go there without them if you need...you told em)
That' mah spit!
