The "gallery rule" is to display artwork's focal point 57 inches from the floor.
Focal point can be person's eyes for portraits, horizon for landscape or artwork's center for all others.
Why 57 inches (4 feet and 8 inches)? This roughly corresponds to an "eye-level" for most people
One side note, artworks that are positioned too high are uncomfortable for us to look at. So better lower than higher.
WHERE TO HANG IN THE ROOM
Sun Exposure. Oil paintings and acrylics will do OK in direct sunlight. While watercolors, photographs and works on paper do NOT like sun and will fade quickly.
Humidity. Most paintings will not do well in areas with high humidity or water exposure. With some exceptions:
For bathrooms, aluminum panels or prints are ideal as aluminum doesn't corrode.
For kitchens, paintings with external protective layer (e.g. glass, acrylic) would do well.
space around artwork
Filling the void
How should artwork match with other items in your room?
A good spot for a painting will fill a void in your room. It will not feel crowded or too busy. But it will also leave enough wall padding around it
For example, 6 inches is usually enough space between large furnuture pieces and your artwork
Notice the "halo" space around the artwork in examples below
If your painting already has a hanging wire attached on the back, please skip to the next section...
Otherwise, we'll need to get the following from Amazon ($10-$15 in total):
Then, carefully attach the D-rings approximately 1/3 or less below the top of the painting.
And attach the wire on both sides
Painting hanging nails
Next step, nails!
Yet, I'd discourage from using regular nails or screws
Instead, these OOK Picture Hanging Hooks are my favorite
They have a very strong nail
They make small holes in walls
They look professional on a wall with brass nail support.
They come in a variety of different sizes supporting different artwork weights
the simple way
Instead of getting individual components like I mentioned above. An alternative is to get everything you need in a nice kit
I recommend one of these two all-in-one Hangman kits:
I haven't tried these kits myself but from the looks of it
They are the best option than buying individual components on Amazon