How do I make Sims 4 more fun?

Quit work, buy an easel, learn to paint.
Shift Left Click on Sim, select cheat need, disable need decay.
Have fun.

I play premades rotationally, its quite fun.

Try starting a sim with no job and a bare minimum lot.. if you buy anything for the lot at all! You just need that mailbox to come home too..

I like to start in the spring in a neighborhood where there are three fishing spots so I can get some quick reward points for following that aspiration part way. I usually also do the beginning of the collectors aspiration because it's pretty easy to get points that way too.

Your first goal is to get the always welcome trait as soon as you can, then travel around living in other sims homes with them. Plan to aspiration hop to set your sim up for a life of ease.

Use their things to skill whatever you want too and fill your sims needs ... and collect/fish/harvest or paint for money. It seems pretty fun to me to make friends or enemies this way. Help other sims or leave broken households in your wake depending on what type of sim you want to play. I usually play a male sim that plants in peoples gardens in more ways than one.
You can usually get enough money skills and aspiration points this way to set your sim up for an easier life when you decide to settle down and get a real job.. if you ever do! You also aren't paying household bills at all if you chose to not set up a home.

When you can buy reward traits to help with needs that bother you the most.. or start buying the most expensive greening items when you actually settle down.

I don't always play this way but I often do for starting a sim or when I don't have a story in mind or not up to sim challenges. I also get a little deviant pleasure by kicking them out of their beds and having my sim sleep in comfort and leech off others... can't help it.. it's amused me on and off since I started playing the game. There are a lot of aspirations you can go at least part way on by playing this way.

I play a full community with council, laws, stock market, nobility and more. It gives variety, and I never find enough time to do everything I want to do, like new build ideas and new services, and more videos. It helps me greatly gathering household info (and more) in a spreadsheet.

Basically, I used lots of imagination in all the sims series. Some sims have jobs that don't really exist, I also have extra notes for DNA that is not in the game, and so on.

Perhaps you can find some ideas on my community pages/residents registry, or on my blog.

I got tired and the same old stuff so I am just limiting my time in game to weekends only until we get new content. Hopefully we will get some new aspirations for kids. I have done it all more than once. Almost 5000 hours played.

I know how that feels, sometimes i'll boot it up and then look at it and think "This is boring". I don't force myself. If I don't feel it, I don't play. Some days I can just type the storylines going through my head, idea's for families, clubs, personal challenges for a particular sim. Adventure with mods, I know some people stay away from them because they carry the risk of viruses etc but sometimes I take a break from their aspirations and lives and just do what I want them to do. Have a weekend fling with someone that is not compatible with them at all, try to hide it from the husband as long as possible- break it off on the monday and then have a very angry sim at your doorstep that you have to hide from your husband somehow......there i go with my imagination.....Wait for inspiration to hit.

I had to change my way of playing completelly to enjoy sims 4. I've always played according to sims traits. I would build my story around traits and the game itself took me to different situations cause both my sims and all non played sims would act according to their traits and made unpredictable things that somehow led my storie.
With sims 4 i had to let go on traits completely. Like they aren't in the game at all. I don't even know what are the traits of the sim that im playing atm. I make up the whole story. I play very slowly. Almost always in speed 1 and pause. That helps me to think more about what i can add to the story. To compensate, as im not a very patient person, im recently playing in short lifespan. Im actually having fun now.
But i miss the unpredictability of previous games though.

1.If your okay with mods I recommend the UI extension mod. This has been a life saver because I can fix moods just by clicking on them also complete the work tasks and even level up skills quickly.

2. Another thing I do is play in premade save files because they come complete with new buildings and townies. The townies also have actual stories and connections to each other so it makes the worlds feel really lively. I recommend: simsie save, simlicy save,aveline save, plumbella save and the Isleroux save.
3. Try some challenges. I'm currently doing the history legacy challenge as it will force me to play in ways I don't usually play in like no electricity or plumbing, growing and catching all my food etc.

Install mc command make up stories. Use kill sim to create a serial killer.

Create a family then use mc command to make them enemies to each other and see how it pans out.

Use mc command to add a very sad mood (depressed) that lasts for 20 days. See how your gameplay might change.

Use mc command to reduce motive decay if you struggle with filling needs.

Use ms command to create complicated love triangle and play rotationally.

Mc command rules.

Haha cool @jimbbq :)
Didn't know that it's possible to change emotions through mccc... i have to explore much more this mod!