Watch this video about using Descriptive Praise with your child.
When they make something or draw a picture, tell them what you like. Describe it, notice it and praise it. For example, "You have drawn lots of yellow lines here and lots of blue ones over here. The lines are so straight. You have concentrated very hard on it. You have made a very nice picture"
This will increase their confidence and encourage them to try that thing again.
Or when they do some behaviour you like, describe what they have done and notice it. For example, "You took your plate to the sink and your knife and fork. You carried them very carefully. That was very helpful, thank you"
This will again, boost their confidence and self esteem, make them feel happy, and encourage them to do that behaviour again.
You can use descriptive praise with any age child. Very young children will understand your tone of voice even if they don't understand all the words. Tell them clearly what you like and this will increase their understanding. For example "You put your teddies in the red box! You found all of them. Very good tidying up!"