Need advice from higher level players :)

Hello! I'm a pretty new farm story 2 player! So far I love it, but I was hoping some more experienced players could give me some insight.

What are the most popular items to buy in shops? For lower levels and higher levels? It seems like some days, no matter what I put up for sale in my shop, it sells out faster than I can stock it. Other days, no matter what I put, it sits and sit. Sometimes even things that were selling like crazy at the beginning of the day become stagnant by noon. Is there a method to the madness? Or is it really just that random? I'm trying to figure out the best items to sell that will be worth my time and not take too long to sell, in case I need to sell something else to make room in storage.

Thanks for any and all advice in advance?

My best advice is help out your neighbors as often as you can to keep a high social rating. The higher your social rank the higher up the list you will appear and have a better chance of others visiting your farm and perhaps checking out your side shop. It really doesn't matter what you sell. I have learned it's the quantity that is important. Every time I try and sell say 10 quiches it can sit there for days until I promote it.....but if I sell them one at a time I can sell out of them in a matter of minutes depending on the time of day.
The only time I really buy 10 of anything is if it's a crop or just a really good deal. I am at level 43 right now and I find my best sellers being pepperoni pizza and quiche tied for first place. Once I upgraded to 12 spaces to sell items in the store I had much more cash coming in. I try and stock the same items and some I have learned sell much better one at a time while others I will sell 3 or 4 of.....I usually only put out a bundle of 10 items if I am able to promote it in case it sits for a few hours.
I usually sell pepperoni pizza x 1, quiche x 1, apple pie x 1, tomato juice x 1, veggie juice x 1, citrus juice x 1, (those are my staple items....then I sell whatever I have building up) any of the jellies/peanut butter x up to 3, salad x up to 3, steamed rice x up to 4, nori x up to 4, then the other 2 slots I just sell whatever is taking up space that isn't needed for deliveries.
The items that are usually harder to find like rice and jellies I sell in higher groups because you usually can't find them to begin with so people buy them when they pop up even if they only need say 1 of it...but are willing to buy 3 to get said item.....but would probably pass on it if it was 10 items since it gets rather pricey if you only needed 1 or 2.
So I only make what I know sells best and then for items I need for deliveries I will either switch gears and make what I need or just try and source it from another farm. It's all about strategy.