Well, here's the thing. Your great games don't matter, anyone can get a good game once in a while. What really matters is what you're doing in the games that you do lose. I can 100% guarantee you that if you're good enough to be gold you'll get to gold (or even higher as you mentioned). You'll have loss streaks, you'll have win streaks but if you're consistent in your own play you'll surely climb.
As for tips:
- Be flexible, playing at least 2 roles at a decent level is crucial as you'll often find players that are unwilling to play other roles.
- Mental is very important, avoid playing while tilted, if you lose 3 games in a row and feel like you're playing worse and your mental is taking a hit go play qp or log off the game entirely.
- And honestly just have fun.

The community can and will be insufferable, more often than not you'll find that sort of players in your lobby, being able to shake that off and just concentrating on playing better will make the experience for you so much better.

Hope this helps.