I am an amateur too but a keen one. I have been on Alamy for about two years. I was a bit amazed when I got accepted then actually sold some images and then eventually got past the $50 barrier and actually got some money!
My day job is as a graphic designer and I work on a couple of small magazines so use Getty images and Adobe Stock a lot and Alamy, and other photo libraries ocassionally so am looking at great images all day. I think it really helps to be inspired by great imagery so I would recommend looking at great images on all the best photo libraries as they will eventually improve the sorts of shots you take as you see how others take shots. Not that you should try and copy them but they can help I find. I have got into reportage a bit over the last year or so, photographing demos and marches. I love the energy. So I tend to look at Gettys news images a lot and see what works.
I would recommend tagging with as many accurate words a possible. Look at others on Alamy to see how they do it. Someone on here, I think, said that good tagging is more important than good tech skills which is exaggerating but without tagging no one can find your shots.
Finally I would say it's a numbers game. When I first uploaded and saw contributors with 1000s of images I nearly gave up but over time I have added bit by bit and now have just over 1000.
I will never make serious cash from this but I love taking photos and if it pays me a bit of pocket money so much the better.
All the best.