Posture, breathing, vowel formation, and articulation explanation

To start off, when using good posture while standing, your feet should be shoulder width apart, knees comfortable and slightly bent, making sure not to lock them, with a tall stance on the balls of your feet and your shoulders rolled back, which pushes out the chest.  While siting, posture should include anything previously said about the upper body, plus sitting on the front or middle of the chair and having your feet on the floor. Having good posture increases one's ability to take a good, full, proper breath, and helps with singing out.
 To continue about breathing, a good breath should come from the down low, and should expand out, instead of up. A full breath allows for maximum control in your singing, allows for strong singing, and helps keep long notes from dropping off towards the end of them.
Next, vowel formation. It is what it sounds like. Some examples are making sure not to keep your tone very tall instead of wide, and keeping your jaw open. This makes one sound very mature in their singing.

Finally, articulation. Articulation is the clarity in the production of notes. Articulating is making sure that things like k's, t's and d's can be heard clearly and easily. Good articulation helps with the understanding of what the lyrics are of a song when it's being listened to.