Experiments can be very simple or very complex. Sometimes the ones that have the smallest changes are harder to figure out.
If there is a food you have made but there is something missing or off, it can be frustrating to try to find out what it is. An example would be cookies or brownies missing salt or potentially nutmeg. They aren’t necessarily apparent, but have a big impact in how the end result tastes. Another example would be switching out sweeteners or citrus fruits or flours, each individually of course.
Like perhaps you want to change lemon bars a bit, maybe you want orange or grapefruit bars instead. Orange is sweeter than lemon so you might just do a 1:1 ratio switch and use less sweetener, or maybe the sweet is the draw so you would use more orange and the same amount of sweetener. This would affect the liquid/dry ratio so be sure to keep an eye on that as well. Grapefruit is sharper and has less tang than lemon, it also has a longer aftertaste. I’m not even sure what outcome you would look for, but it makes a fine example nonetheless.
My cinnamon rolls are an example of something where I was looking at what ingredients I wanted from other recipes of similar type and what I wanted to add. It’s not the most complex change by far, but it is an example of a large change. I knew I wanted shredded cheese, cream cheese, and almond flour as the base. I looked at the old cinnamon roll recipe as well as a couple bread recipes to help come up with a good ratio for the cheeses.
If experimenting is something you are going to try, which I encourage, you will definitely want to write everything down as you do them. The only times I do this is when I pre-plan a change in recipe, not when I do it on the fly. Which, while I like being able to do that, makes it very hard to replicate unless I remember precisely what steps I did and what amounts I used.
If there is a taste you enjoy, it can help your experimenting as well. Such as liking caramelized onions or roasted garlic. They can be added to many things as a side or a background ingredient to enhance flavors.
Knowing how much seasoning you like on things is a tremendous help too. That way seasoning amounts is not a guessing game, and depending on what you are making, the type of seasoning might not be a guessing game either.