My general impression from the comments in the various subtext posts makes me think there's something of a general confidence crisis on this subject. This is unwarranted. Every day, you interact with people and watch their body language and demeanor for clues to their internal states. You have a lifetime of practice in interpreting subtext in day to day life. It's really not that different in fiction.
Perhaps the difference is in familiarity. Perhaps as writers we have it drummed into us that we must make everything absolutely clear to the reader. We take this to mean everything must be spelled out in precise detail, leaving nothing to the imagination. But clarity is possible even when we rely on clues rather than direct statements.
Tears streamed down Jessica's face.
Jessica was sad.
The first gives a visual clue to an emotional state. The second tells the emotional state. Which is more vivid and engaging? The first. No contest.
So here's what we're going to do. We're going to practice. Practicing will give you familiarity with the technique, which will increase your confidence. I'm going to give you an action by a character. In the comments, I want you to give examples of how this action could be used to demonstrate TWO different emotional states. Do this twice because it will force you to think about different ways to interpret the same action. Context, remember, is crucially important in staging subtext.
Here's your action:
Henry skittered backwards in three quick, light steps.
Now link that to an emotion without naming the emotion. You can do it. It's not as hard as you think.