I'd say that the first step is to work on composition/subjects.
Professional have better materiel and skills, and there is also a lot of work editing the pictures, but if your subject is not interesting and your composition is boring the pictures will be bad no matter what.
Look at pictures or paintings* that you like and try to understand how the different objects are placed - the strength lines they form, where they are in the picture...
When you take a photo of a foreground subject (like a person, an animal), try to have a nice background (and to wait patiently until any unwanted tourist has left the field !). Don't put your subject in the center, but try to put it at one third on the left or the right - unless you want to emphasis symmetries or stability. Have horizontal lines to give a feeling of stability, vertical/diagonal lines to give dynamism, and put your subject at the intersection of your main lines to direct the eye to it.
Also an easy improvement is light : forget about pictures inside, they are almost always bad. Don't use a flash, artificial light is hard to use well. The sun is your best friend, but you should always try to have it in your back when you take a picture - that way the subject is well lighted and you avoid being against the light. Sunset light makes any crappy photo looks good.
Similarly, great color contrast helps a lot, but it is very hard to take a good picture when the subject and the background have similar colors.
*I'm not that much into still-life but I think they are great to look at compositions.
The problem with general advice to look at YouTube instructual videos is that if you don't have any skill in the subject, you have little way of knowing which instructors know their craft well and are good at teaching it.