When playing side out scoring during volleyball, the serve is the most important part of the game because you only get a point on the serve. However, you need to have your serve in rally scoring too since every time you miss a serve; the other team gets a point.
If could stress anything, it would be serving. If you can't serve, you're basically helpless. This is because you're giving the other team points when playing rally and you're not scoring any when playing side out scoring. Also, if you can't get the serve, there's no action going on and what's the fun in that? If there's anything that you should be a perfect at, it should be serving and I can't stress that enough. To get better at serving I would just do volleyball serving drills over and over again. There really aren't many drills that you can do, but I'll name a few common ones.
Volleyball Serving Drills:
- Do a lot of arm exercises so you don't pull anything because you'll probably be serving a majority of game compared to everything else
- Serve about 10 times in a row and do a couple reps, but don't do 40 in a row since you're arm will get wore out
- When serving, do the same thing every time you serve, don't try something new because you may mess up
- Don't rush! Too many people rush and it completely messes up their serve
Also see volleyball training aids for more details.