If you’re not already in a guild, you should definitely join one as soon as you can. The benefits of being in a guild are humongous, as there’s no downside… unless you join a guild that has requirements, such as “earn max seals and contribute x amount of gold each week”. In that case, the downside is time investment.
I recommend only joining guilds that are okay with you not contributing gold yet, because you need that gold to gradually level up kingdoms.
Most active guilds would require you to earn trophies then, which are earned by invading other players and winning.
Then, there are the mega-laid-back guilds that don’t need you to do anything, they just want to see you playing every so often. Like my guild: a chunk of players don’t contribute much but still play the game, as evidenced by the seals they’ve collected. (You earn seals just by playing normally, if you’re in a guild.)
I didn’t play Gems of War for like 5 months and they didn’t even kick me out. Then I came back and started playing again, and now I’m suddenly the second highest rank in the guild. I guess the leader appreciates my seal earnings, despite us not speaking the same language…