Need Help & Tips for Improving Sims 4 Gameplay – Any Recommendations?

#4. Tips on improving game performance.

Dag Dag to Lag: Improving The Sims 4 Performance | EA Forums - 12913577

Edit: #2. What packs do you already have?

1. I have very few mods, mainly mccc and fixes.
2. Good expansions depend on what interests you most. Do you already have some? If you like fantasy, I would recommend realm of magic or werewolves. For family gameplay I would recommend growing together or parenthood. If you like your sims to run a business, businesses and hobbies might be your thing. You could also get a pack like seasons, get together or adventure awaits that have a more broader approach.
3. I really enjoy playing with my supersim and complete aspirations. Rags to riches is also a fun way to start a new household. If you want you could also go for a scenario.
4. I think the link from simgirl1010 should be a good start.
5. Depends on personal taste. No idea what to recommend. 

I don't have ideas for every point in you list but here is my way of gameplay:

[if your not interested in "perfectionating" you sims-world this may not fit, it's VERY nerdy...]

2. I like Expansion packs which gives my sims more "character". e.g. Cottage living, Island Living, Stranger Ville, Horse Ranch, Eco Life Style or also For Rent. (also some accessoires Packs are very nice for individuality.) But as atreya33​ already mentioned, this depends on you own interests of course).

3./5. I love spinning wheels and similar tools, (which are often used by James Turner e.g.) for new born sims. For every new born you randomize clothing style, favorite color, aspiration and hobbies etc. As soon our sim move out you will get a new challenge for CAS,  building and earning money. I never use money cheats, so if my family don't have enough money which could the next generation take to their new home it's gonna be a rags to riches under special conditions. This can end up in very funny and interesting combinations.

also 5(b).:

In my main game I started every World with exactly one couple or single sim which fits the style. I play them rotating. And at this point it really gets very nerdy, because I need a separate excel list/ family tree to manage them, especially with realistic aging.  When it comes to a new generation my sims usually have children with some of my other sims. I really enjoy to watch the genetics of my sims.

So, if you're not planning to play sims in most of your free time instead spending time with family on Christmas 5(b) may be a bad idea. But the spinning wheel for a rags to riches is always nice!

Mccc mod is a 111% Must-have

Another mod I'd recommend is "Fogity Hidden Highlight" ! It's an older mod (2016, I think), but it STILL works! It gets rid of that annoying highlight around Sims, when you put your cursor on them - makes for better screenshots! 

1. Mccc is the only mod I have. I'm still navigating it
2.  I have quite a few of the packs. It depends on how you want to play though-like occults vs. non occults, etc. 
3. There's so many! Not to mention possibilities yet to be discovered. I like the idea of The Achievement Challenge going around. (Play 10 different legacies in one save.) But I don't have the wherewithal for it...
4. I'm still experimenting with this. 
5. I'm currently trying to figure out how to adapt rosannatxt's "Origin's Legacy Challenge", to my gameplay style. 

I'm also here to see others' ideas. >.> 

I've always enjoyed the challenges where you play only one Sim in the household and let the others do their own thing. Or a modified version, where you play one Sim a day, so that everyone improves skills but slowly.