Gaining levels

So Im not sure how to use this Forum as I didnt know this existed until now but I feel like while many users I see are in Level 99 etc I am still on level 19, despite playing fairly actively on and off for several years. Am I missing a trick? I learn more every day but I feel like I am missing some sort of information about leveling up, getting XP, etc. I want to expand and make my restaurant better but I feel like it is hard. I also dont see how people manage to have full counters of food all day! Are these people just on the app a lot or again, have I missed something?

Any help would be appreciated :)

If you want to keep leveling up On this game, spend your money on the decor like tables, chairs, wallpaper, floor decor.. Buy counters, stoves.. Play the goals..

I was amazed too seeing people that always had food, to achieve it myself I closed the restaurant so people couldn't come in and started cooking the same dish in all my stoves, and then another and then another I used long recepies, that's the way I did it but it takes a lot of pacience and having enough money to get by without costumers