Farmers have no career option in the game, but they should

@NennaRC you can set their job title as Farmer by going to the phone and selecting Register with Ministry of Labour. Then you just need to add their job title in the top box and the name of the farm in the next box. I do this with all of my farmers and actually for my retailers too. It's a handy little option. Or I call them a Rancher if it's a ranch. It will then be displayed in the career panel and in conversation when a Sim asks about their career.

With the finances, there's a trick to earning more from crops and making the farm a lot more profitable. If you haven't noticed before if you sell harvestables (but not CoL crops) from the Household Inventory in build mode they sell for a lot more money. You can also sell them a few times in the window between them producing harvestables until they stop within about an hour. So if you watch them at around 5ish, pause then go into build mode and take them into the inventory then put the plant back and sell the produce, then go in and out of live/bb mode and repeat the process. On the downside it takes a few minutes (and on console we don't have a Sell All function 😤) but I feel the benefits outweigh the inconvenience because it's a real money-spinner. If you're quick you can make quite a lot of simoleans and if you have some plants like Dragon Fruit, Orchids, Death Flowers for example you'll do very well. But even if you just have Strawberries or Roses or Pomegranate trees you'll not do to badly either. I often tie it in with the Making Millions Scenario and get the Reward Points too. If you have Seasons it will obviously be seasonal so you'd need to plant accordingly. I also try and get a Money Tree seed. Sometimes the little stalls have them, I've got them from a Crumplebottom before.

I haven't sold any livestock as I get a bit too attached lol so don't have any tips for that. Actually you might have hit on something there with creating pedigree horses in CAS then selling them, I'd never thought of that!

@simsplayer818 Yeah, all these are great tips if you play one or a couple of households but not if you play rotationally. As I said in another post, I play currently 36 households at a time which means that I spend only 1/36 of the time in each household and I need to know that the sims can sustain themselves with enough income to pay their bills also when I don't actively play their household. If it was possible for them to sell produce such as honey, milk, crop, veggies, juice, wool, knits, fish, seashells etc. in their shop or road side sales tables, also when I'm not actively playing them, then that would be a great solution. And don't get me wrong, all you tips are great if you concentrate on actively playing one or a couple of households. It even fills the game play if you play such a way with more activities and content for you as a player. But for rotational play it doesn't work. Income needs to come in regularly then so I still think it would be a good idea to make Farmer a career option. Or, even better, make it possible for us to set up our own careers by choosing a job title, which income ladder it should have and how much increase per promotion, which days a week to work and which days are holidays. That, if anything would be a dream come true and would open up for very fun gaming. We could even choose the job outfits for all the different promotion steps and we could create whatever jobs we wanted our sims to have. It is great that we can set a job title as a self employed sim but it doesn't give us any income, it's just a title now. It's good though, a good beginning and a great tip if you don't play rotationally.

@NennaRCit's lucky they don't pay bills when you're not playing the household. But I was getting 2 lots of bills for them in one week when playing rotationally, so I switch at the weekend before bills are due. I did a test on it recently and found that switching back to them on a weekend meant only one set of bills. But switching in the week meant double the bills.
I'm on console but I'm told there are mods that make rotational play easier for PC players. We can only use a couple of cheats too without affecting console achievements.
I also try and switch to another household after work hours or it's telling me they haven't gone to work and it was affecting their work/school performance. It was all flashing red lights on their school and career panels.

Edit: just thought of something else I do when playing rotationally. As I always start these groups of households in batches in one household before moving them on to their own. I complete the Making Millions Scenario along with the Mansion Baron and fortune aspirations. That way I can use all of those reward points. I get the Steel Bladder one first as it's essential IMO. Plus Carefree and Connections so they start the career higher up. I add Professional Slacker if I have enough points because I like to add the skill building ones too as a priority. When I've got a few households at a time I want them to learn faster and get promoted faster.

@simsplayer818 yeah bills are yet another thing that don't work when you don't play the household. It should work just like normally so that the sims lives work properly also when not actively played. To have to provide money for them with cheats to make it work to play rotationally is just not the way it should be.