If you aren't hitting at least one serve out per match, you are not trying to hit great serves.
The idea
Great serves don't have to be high and near the out line, especially against new players, but high backhand volleys present problems for the vast majority of players, so that area makes it perfect for getting weak returns. A good serve is one that causes your opponent doubt and hesitation, which then creates weak returns, which then create opportunities for you to attack.
What to do on court
Finish every single court session with some high lob serves. It's not rocket science, but it does take discipline. Stick small boxes or at the very least a sticky note folded to make a good target. You could even have a little match with your playing partner using the sticky notes: first one to hit it, the other has to buy the drinks or supply a new ball next time you play.
