Here's a top 10 list of my playing habits:
1) When creating sims, I tend to colour-code them and give them outfits and accessories in their favourite colours. That's something I already did before colour preferences were added to the base game. I try to use all traits, but some (like Creative, Loner, Ambitious, Loves the Outdoors) tend to come up more often than others (Freegan, Jealous, Lactose Intolerant, Non-Committal). One trait I almost never give my sims is Outgoing because all it does is deplete the social bar faster, and that's the need that already gives me the most trouble as it is.
2) When moving sims into the world, I build their house first and give them just enough money to afford it, but from then on, they have to make a living without cheats. (This quickly became problematic with Croft Manor in the beginning, as the weekly rent was roughly 26,000§.) Cheats in general are only used to set up new households or deal with the game's bugs and unfinished features.
3) Sims can't just move wherever they want. Every world in my game has a specific theme that is reflected in its population. For example, every household in Brindleton Bay must include at least one pet (which can be a cat or dog, but also a farm animal), residents of Del Sol Valley have to be (or aspiring to become) famous in one way or another, and the worlds from the occult packs are mostly reserved for their respective occults.
4) The first thing I do after moving in is make sure everyone has the jobs, beds, umbrellas, and mobile phone colours I want for them.
5) While I play with sims of all ages, with varying backgrounds and life situations, most of them are practically-minded creatures who focus on their individual hobbies and careers above relationships (which should explain my trouble with the social bar). I don't usually play romantically, so most of my married couples are created that way in CAS along with their children.
6) Every member of a household has a clearly defined role and tasks associated with it. I've never had to call a repairman or gardener before because there's always at least one sim in the household who takes care of those things. The only service personnel that some of my households get to have is maids, which isn't actually necessary for what little cleaning there is to do in the sim world (I wish it was like that in the real world...), but some families just like to show off their wealth and prestige.
7) As a huge fan of magic and the supernatural in general, I may not have an occult sim in every single household, but there is usually at least one per neighbourhood. A notable exception is Foundry Cove in Willow Creek, which has quite the large population (19 sims across 4 families so far) with not a single occult in it. But there's still one empty house left, so...
8) A recurring building trend in my houses is to have a fireplace in the living room and a TV on the wall above it. Also, every household does laundry, so there's equipment for that in every house as well.
9) I used to have ageing enabled (long lifespan) for currently played households, but still kept every sim at the desired age with reward potions, magic, and other in-game methods. However, I permanently disabled ageing last year when the ageing bug appeared.
10) I don't let my sims die unless I want to play with them as ghosts or get rid of them. There was that one time I accidentally enabled ageing for all played sims rather than just the current household, and several elders died off-screen. Thankfully, I was able to bring them all back with ambrosia.
