How is the best way to tell wrong side and right side?

I am not very experienced with knitting. How do you tell right side and WS in just straight knitting, not k/p.

In garter stitch (every row knit) The knitting is completely reversable. There really isn’t a wrong side.

I thought that too until I put my Child’s garter stich sweater together & got a line that looked indented onthe back(luckily).

You can hang a stitch marker off of a stitch to indicate the RS, if you like. Otherwise, like Vicki said, you can’t tell the difference w/ garter stitch.