First things first: Why in realistic fiction, exclusively?
Because that’s what I write myself, and the majority of what I’ve read has also been realistic fiction. I don’t feel qualified to give advice relating to speculative genres.
1. Keep descriptions brief.
This does vary, depending upon the type of story, and your own particular writing style – but, in general, modern readers don’t appreciate page upon page of descriptive writing. Mixing it up with other elements, such as dialogue, can help, as it does make it much easier to consume.
2. Use specific details.
Yes, this does come under the “show don’t tell” umbrella. If there’s a tree, is it an oak tree? Lime tree? Birch tree? It makes a difference, and makes the scene feel more authentic, if we have a little more information – and it doesn’t exactly require many additional words.
3. Use all five senses.
A sound or aroma, for example, might be the extra touch, that brings a visual image to life.
4. Be inspired by real places – but, at the same time, not confined or restricted by them.
The amazing aspect of writing fiction for me, is the blending of fact and fiction, so don’t be afraid to mix it up.
5. If you find that you don’t naturally include much description in your first draft – don’t worry.
I personally tend to write mainly dialogue, and minimal narrative, initially. It’s easy enough to add more description during rewrites, and anything that slows down your writing process should probably be avoided. My post on White Room Syndrome is particularly relevant to this point.
I hope that this short post has provided some useful suggestions, to help you with the important task of bringing your realistic, fictional settings to life.