The easiest way to make a posted image look good is to use the correct size picture.
That’s it.
Unfortunately, the proper size is not always a round number & they regularly change.
Here’s your 2020 guide to sizing pictures on LinkedIn (plus FB, Instagram & Twitter in the comments):
Bookmark for easy reference!
LinkedIn:
Image in a post: 1200 x 627
Personal cover pic: 1584 x 396
Company cover pic: 1192 x 220
Profile pic: 400 x 400
Twitter:
Tweets with 1 pic: 1200 x 675 each
Tweets with 2 pics: 700 x 800 each
Tweets with 4 pics: 1200 x 600 each
Header photo: 1500 x 500
Facebook:
Image in a post: 1200 by 630
Stories: 1080 x 1920
Instagram:
Portrait: 1080 x 1350
Square: 1080 x 1080
Stories: 1080 x 1920