When looking for a good tennis pro, try asking the students of the pro you're interested in some questions like:
1. do you have fun ?
2. do you hit lots of balls?
3. are you physically active?
4. does the coach listen to your needs?
5. is there good feedback?
Look for a coach who asks you questions like, "What level are you?" and " What can I help you with?" You want a pro who listens to your response and asks some follow up questions like: "when you say you're having trouble with your BH do you mean when you rally or when you return serve?" Beware of the coach who thinks they know what you need without asking anything after only "rallying" with you for a minute.
The USTA did some stats a while back on why people stop taking tennis lessons. The #1 reason was the coach tried to change them. If you're doing "major surgery" in your first lesson and you haven't agreed to it.. you're with the wrong coach.
You want a coach who gives you specific targeted feedback on one thing at a time. Beware the coach who barfs out 7 different things you're doing wrong in your first three shots. Great coaches will highlight your correct performance rather than continually harp on what you're doing wrong.
Ask lots of questions of your coach. Good coaches will gladly answer how what they are teaching you connects to the "big picture" of how your game is developing.
25 years of coaching experience doesn't always mean you've got a great coach. It might mean 25 years of doing the same old thing. Tennis is constantly evolving and so are coaching methodologies.
Ideally, you want to find a coach who respects coaching education and is curious about finding new ways to improve player performance. But most of all you want to learn the game from someone who makes it fun!