What should I prioritize in tennis before tryouts?

Okay, so I'm a junior in highschool and I am trying to join the tennis team in my school. I'm a left-handed player & also the ONLY left handed player that will be on the team if I were to join. My forehand is alright, but my backhand is horrible. I'm 16 years old and I'm just using a beginner racquet so I can just focus on getting my form and techniques down. EVERYONE on the team are right handed players, so they'll most likely hit to my backhand during tryouts which are coming in about a month. I also don't have a serve. Oh yeah, everyone already has experience from the previous school year while I'm the only new player as well. What're some general rules should I keep in mind while hitting? So far, I have : 1. Hit while sideways 2. Flat racquet face 3. Swing low to high 4. Always stay balanced 5. Always on your toes