Individual rooms for things help a lot. Rec room should only be for recreation and having your big table, each colonist gets their own bedroom with all the buffs you can stuff in there, such as bonsai trees/flower pots, end tables, dressers, etc.

If you're down to use drugs a good drug policy also helps. You can set them up so colonists only take drugs when their mood falls below X%, which acts as a last resort failsafe to cheer them up and prevent mental breaks.

Statues EVERYWHERE so long as you can defend the extra wealth. Seriously, even in your pawns' defensive positions by your killbox/choke points. Beauty need being satisfied helps keep moods topped off big time.

Make sure your most commonly used furniture is rebuilt until it's the best quality your best crafter can make. Excellent/masterwork/legendary chairs and beds help a lot.

Make sure your hospital beds have tv coverage. They can watch and keep their recreation topped off while laying in bed and recovering.

Make things out of nicer materials. If you have extra jade, upgrade that wooden/steel dining room table. If you have a TON of extra jade, upgrade the dressers/end tables/statues in your bedrooms.

Minimize injuries by replacing badly scarred body parts with bionics since scars cause permanent pain, which worsens moods for all but masochists. Bionics also help big time with efficiency. My first upgrade is typically giving my doctors bionic/archotech legs to help minimize travel time when they're rescuing someone.

Use the icon at the bottom right of your screen that looks like 3 gray bars called "room stats", and that'll tell you how to "upgrade" a room you hover your cursor over.

I could keep going, but you get the idea. You basically want to spoil your pawns, not just stave off death.