Try Peter Elbow's book on "Writing with Power". he recommends a lot of different techniques to get you started and improving. The best way of building writing skills is by writing. Practise every day.
I used to make a 20 mile drive to work through heavy traffic and would work out a description of my drive which I then wrote down longhand in a notepad as soon as I got into work (no computers in those days). It might have been a description of the weather or the traffic or the road.
When my children were going to sleep, they liked to have someone stay beside them and the bedroom looked out over the sea, so I composed sentences describing the sea at that time. I was able to use those snippets later in other writing.Sometimes, I could not get a good description of what I saw but I would write it down as best I could and maybe a few days later, the words I wanted would come to me and I could edit it.
In work, some of the people I worked with had English degrees. I used to look at how they wrote and try and emulate their writing, in my own way.