My strategy for this challenge was centered around a few observations:
1. Like in every high school movie, sims don't have to be liked to be popular
2. Playing for tips is probably not the most lucrative source of income (i.e, it was faster to get $1M followers than earn $1000 in tips)
Manager was the focus on my time and efforts. From the last challenge, she had gained an atrocious reputation, was a 2 star celebrity, had the connections rewards, and had ~10,000 SM followers. She started by joining L3 of the SM career. She gained more initial followers using the drone and using the various interactions unlocked by the SM career as well as the upload viral video (unlocked at L10 charisma) and had the possibility of earning her >1M with one click. She used her reputation to bribe her boss until she reached L8 of the career (which took 1 sim week), at which point she unlocked the highly valuable, and extremely broken stream "lets play" interaction under the play video game menu. For some reason, the sims team designed this so that 5-star celebrities would get 1.4M followers without any time, so she cued up and ended a bunch of these interactions. Since this was pretty boring, I decided that I would stop at 500M followers, at which point Manager would sit around and periodically go through the rest of the SM interactions whenever the cool down period ended. "Prank streamers," "upload viral video," "promote image," "start funny meme" all that had potential to earn 30,000-2M+ followers.
For the musicians, I recalled the game had a silly rule where it was only possible to license a single song per instrument per week. Thus, the musicians - Billie & Elsa - had each written 3 songs on 3 different instruments in the last challenge, and immediately licensed them. I was dubious they could make that much money from playing for tips, so they focused their time on writing more songs. They spent the next few days writing a song on the fourth instrument (organ for Elsa, piano for Billie) and licensed that as well, as well as additional songs on the four instruments. The next four songs they licensed the following week. It wasn't until later in the challenge, I realized they could also write a mix-tape on the DJ booth, and license that as well (so my eighteen songs game from 2 violin, 2 piano, 2 organ, 2 guitar, and 1 DJ booth).
After they finished their song writing spree, they went on their musical tour. They generally played violin at a bar/night club until they got a few tips, at which point they moved onto the next. For the residential worlds, Newcrest + Forgotten Hollow, they did busk on the City Living busking station (which felt like in the spirit of the challenge) and "Helper" tipped them (though this did not change the net value of the household income). After they finished the world tour, they set up shop at the Planet Honey Pop Bar in San Myshuno (this was also a good location since Manager could sit at a table with a portable laptop and do her SM interactions).
Ultimately, most of the household earnings came from their royalties, which was boosted by the marketable rewards trait and the "established name" celebrity perk. There were some days they netted >$7K in royalties alone. Manager also earned a fair amount of simeloeons by getting promoted to L9 in the SM career by the end of the challenge (though also burned a fair amount of simeloeons through bribes)
In terms other set up from the last challenge - before it ended, I made sure to purchase 2 violins, 2 guitars, 2 portable pianos, 1 portable laptop, and 1 organ for this challenge (so it wouldn't have to come out of the starting household funds). I also deleted all the other furniture except the toilet to try to minimize bills. Helper had a constant stream of plentiful needs potions (which was boosted by the copypasto spell) to address all other needs.
Stray observations
1. The SM followers function in the Sims is very simplistic (you essentially get within a narrow range of followers for almost every SM interaction, whether it's the drone, SM interactions on the phone/computer, or the "Lets Play" interaction for video-gaming)
2. The most lucrative way that I found to earn tips is to use the busking station, play long enough for a crowd to gather around, and then click the "solicit tips" interaction. I could get ~$100 in 1 sim hour.
3. Manage purchased the trailblazer perk. One of the effects is that all the sims in the world will wear the same outfit as your sim. It took me a while to figure out why everyone kept wearing the same outfit!
^Here, Lily Feng, Kayla Flemming, and Billie Jang are all wearing Manager's outfit (which ironically Manager didn't even wear throughout the challenge)