So I'm starting to get back into landscape/still life painting in oils. Here are some oils i did from West Virginia photos I took. The top picture is the photo on the left and the painting on the right. A couple things I have learned:

Drawing and figuring out the composition is key!
Values are way important. Compare all the values in the subject matter. The sky might have darks and lights, but the darks will never be darker than the barn shadow.
Squint a lot.
Stand back and look at your painting and subject often.
Start loose and then tighten.
It's ok to make errors. You learn from them. It doesn't have to be perfect. What is perfect?
When painting darks, thin them out with a mix of stand oil, Linseed oil and terp or just terp.
Lights can have a little more paint.
Don't use black. Make a good black from Ultramarine Blue, Cad Red Medium and a little Cad Yellow. You might think the yellow ochre would make it darker. It doesn't. Yellow Ochre has a chalkyness to it, so it would make a dark grey, not black when mixed with Ultramarine and cad red.
I use a product to dry the oils quicker (liquin).
Rub some cad red and burnt umber on the gessoed board. It really helps. Sometime you get these great parts where the background shows thru.
Oil Medium Video: https://www.youtube.com/watch?v=0wIbnG1UCLw
Try to paint something every day and Have fun!