@Josulyhar So, I don't know if this helps or not, but...
I think the designers assume you get a single Sim or couple or small family and move them into a starter home and build their way up to that amazing, awesome lot.
That said, I recently, for a self-designed challenge, gave Vlad a wife and children and started playing them on Vlad's lot. He has a lot of really expensive items so his bills are around $4k, and I decided Vlad and his wife would not have jobs and would be stay-at-home parents.
So, what I'm doing for money: Vlad comes with a really high pipe organ level, so I immediately had him write a pipe organ song and license it, and then mentor his wife on the pipe organ. You can re-license songs forever, but only for one instrument at a time, so after they started getting pipe organ song money he started in on piano because he already owns a piano. Vlad doesn't sleep much and has all the vampire Child of the Moon bonuses to skill gains, so he was quickly able to learn every instrument and write and license songs for all of them. His wife isn't the speed demon he is, but she's also writing and licensing songs.
In the early days, I would also have them go to nightclubs and play for tips, which isn't an amazing amount of money but helps. If you're level 10 you get like $10 or $12 per Sim who tips you, so he wrote his piano song in public and got paid for it.
His wife got into high-end gardening in that covered balcony area and that's also regular income. If you have City Living and go to the Romance Festival, there are also high-end plants there you can harvest and plant at home. (If this is for money, don't waste your time with veggies, especially if you're playing vampires. Roses and dragonfruit and Birds of Paradise and Orchids. If you have a roof over them they'll grow year-round. Veggies are amazing for cooking and the Simple Living lot challenge, but we're talking about filthy lucre.)
They both then got into painting and Vlad has started writing books, because you can have so many of those that they scroll off the screen but you only get royalties for 30 days for those, so we're still relicensing our songs continuously.
So, at the moment they can easily afford their $4K a week bills and Vlad is a 4 star celebrity (ROTFL). His wife is a 3 star celebrity.
So, yeah, your Sims will need income, and some ways are better to get it than others. Starting a career at level 1 is probably the worst, alas. You might want to put your Sim in University, if you have that pack, so they can start at a higher level, but it still won't compare to licensing songs, painting, and writing over time. Also, the freelancer careers pay pretty well, and if you're industrious you can ramp up pretty fast.
Good luck!
Edited to add: However, the single most lucrative activity in the game, hands-down, is to be a spellcaster and dumpster dive for deals. You'll get a lot of really expensive items that you can Repario and sell. My teen caster became a Virtuoso almost exclusively from this and Scruberoo-ing himself afterwards.
Also, other people have mentioned Frugal and the Shrewd reward trait, but if you're going to sell things I would also suggest Marketable, and also the Home Studio home lot trait, and Creative Visionary if you're doing creative things for money. Also, bathtubs on the woodworking table are pretty lucrative. With Get Famous, the tree starting with Noticeable is the one you want so you can get Established Name, which makes your songs/books/paintings/other created items worth more money. My Super Sim has this and once sold a single painting for $20K.
(As for getting around the money limit, I have fake businesses/"vacation homes" and dump funds into those.)
