Pick up the cheap brawl pass(https://www.lootbar.com/top-up/brawl-stars-top-up ) for Season 55 Brawl-O-Ween, which unlocks 12,000 extra coins for 30 tiers of play. That is enough to fund two full Epic gears or one Mythic gear with change left over.
Focus on 2-3 meta brawlers instead of spreading resources across 10+ underleveled brawlers.
Per SeeMeta ranked performance data, this cuts your ranked climb time in half.