I think the most important thing here is patience. Here are some things I did.
- My sim lives in restaurant. Usually, she opens the restaurant then take a nap when customers are being seated. Also, she frequently uses the potion (sleep replacement and Moodlet Solver) which she can afford from the Fortune Aspirations.
- I started with Hogans Burger Bar > Chez llama > Villa Bovine > Sunnyside Up Diner > L'attente Bistro. Generally I bought more expensive restaurants first so that I don't have to worry much about money. Bistro was last because I like its open space.
- The restaurant is open for a 11-12 hours shift and closed for 2-3 hours. I try to schedule so that it is open during the rush hour (10 am - 2 pm and 6 pm- 9pm)
- She only serve level two food and always use 25% organic ingredients to keep the customers happy. Also decoration is very important to get 5 star.
- I only hired young adult and adult, never elder and pay them well to keep them happy.
- It doesn't matter much whether I can hire the previous employees. I always train them and they will be good enough to get 5 stars in 3-4 shifts anyway. For the last restaurant where I spend most time with, employees are very good, chefs cook at fast speed and I used Fast Eaters to maximize the perks.
- I sell the first four restaurants as soon as they reach 5 stars so that I can focus on just collecting perks on the last one. For the first four, I often comp food especially if there is only one customer. Welcome, check on table and prioritizing food are the must for all tables in every restaurant.
- I found that recommending the dish cause glitch, so I often skip them. To avoid glitch, I have a strict schedule. My sims will check on table, welcome and prioritize food after the waiter got their order. After they got the food, she comp food. This means that in the last restaurant, I got a maximum of 25+25+25+25+35 = 135 perks per table. Note that since the chefs are good, I sell higher level food with higher price to get money to comp food more.
- I always use Meal Rush and advertisement.
- Based on these strategies, it took less than 48 hours to get 5 stars and I got a few thousand perks per shift.