Traded my WHI cards for 2000 CoC cards.
I want to build a couple of decks for casual play with friends.
Any tips?

My main tip is "have fun!" Come up with decks that have interesting themes to you, play some games and then you'll start to get a sense of what you like or don't like about certain cards.

Since you want casual play, I wouldn't worry about trying to make the optimal decks, so just go with what feels like fun to you. Thematic decks can be quite enjoyable to play even if they don't perform at a high level - you can start to "live out" a story as you play the game.

You may want to head over to CardGameDB. There's a separate deck section with currently 127 entries. Many decks include hints about strategy etc., so it's a good place to get inspirations.

There's also at least one article series with concrete in-detail decks.

The beauty of CoC is that you can mix-and-match between factions as much as you like, so you can get every combination to work, especially in a casual environment and with such a large card pool as you already have.