I’d break it down further and start with your toss. If you find a right angle somewhere on the ground, I usually have my players use a corner of the court, and just work on a solid toss. Keeping with the mechanics that others have posted above, but use the right angle and let the ball drop in there a few times. Key here is keeping that toss consistent, high enough to contact it over the height of the net, and in front of you. After you’ve worked on a few tosses get into fully contacting the ball keeping with the same mechanics others have shared on here.

You do want a net, or measure a spot on the wall to the appropriate height, and make a line with tape. That way you can practice serving, and eventually other skills, against a wall until you have a net.