I made my Sim with some generic good-moodlet traits, I think good, insider and loves the outdoors. I also made her like wellness and new age music (though any other kind of music would have had the same effect).
I put her on a lot in Newcrest and a gave her the bare minimum: a very tiny home, a radio, a regular yoga mat, an instructor yoga mat, a meditation stool, a massage table and chair, a crystal crown, and later a bush (served as a toilet) and a cheap shower. The last two were as a courtesy for club members. She joined the Good Timers club and took over in the first few days. I wanted to use the crystal crown for hygiene, but computers are expensive and you can't buy crystals from a public lot. So she travelled to the Magic Realm, and I was very lucky to find a ruby in the shop there. She used that for hygiene, and between that and Rally the Troops, she was set for needs. I also used custom costume holidays for extra good moodlets.
She practiced yoga until she hit level 2, and then started to teach a yoga class right away. While she was still skilling, she stayed on the home lot, so the victims customers were club members and anyone who walked by the lot. For the first week and a half the routine was pretty much: give a yoga class, give a meditation class, give a massage to anyone who had attended both and was still around. If, and only if, anyone had all three of those marks, they qualified for mani-pedis, followed by a selfie to push the relationship to good friends.
When the skill was maxed, she mostly went to Willow Creek Park during the day. She would first give a single massage to allow more Sims to spawn and then start a yoga class. I had anything from 2 to 11 people attending the class (and not walking away halfway through); typically 6 or 7. I experimented with different locations, but I couldn't find a place that has as much space as Willow Creek Park, including the prebuilt spas, which have fairly small yoga studios. The park in San Myshuno has the opposite problem: way too much space, most of the Sims were too far away to attend.
During the night, I typically went back to the home lot with just the club. The club members were rotated depending on who I wanted to treat. The nights were used for massages and manicures / pedicures.
Near the end of the challenge I decided to just go for money and spent the last days only giving yoga classes and massages.
I suspect a much higher score could have been reached with fewer friends and more focus on lucrative activities. Manicures and especially pedicures are just so time-consuming! There was also a lot of queue freezing and other Sim shenanigans, but that was true for all five activities. But at the end of the day, at least there are now a lot of Sims with fabulous nails.