Instead of opening one photo from a folder try this.
Launch Preview, it's in the dock, and then choose File > Open and navigate to your folder.
Select the folder and click Open.
Then, in Preview, go to View and check Thumbnails. This puts a list of thumbnails down the side of the Preview windows and hitting the left and right arrows, on the keyboard, you can scroll through them.
There are other options in the View menu.
I had the original OS from when I bought my Macbook Pro in 2011. I just upgraded the OS to El Capitan. With the old OS, when I had photo up from a folder, I'd 2 finger click on it, and "open with" ( I think ) image viewer. When I'd open the picture, a menu bar came up along the bottom with small icons of the photos in that folder, and I could click on a photo and choose to open it to full screen ( or fit to window, or 150% , or edit, or whatever ), then use the arrow keys to go to the next photo.
In El Capitan, the "open with" only give me a choice of "preview ( default )", and it doesn't work like it did before, I can't move to the next photo with the arrow keys, I have to close that picture and click open the next one. How do I get it to work like it did before with the arrow keys at full screen size?