I played tennis all my life and college tennis for 3 years. I recommend finding a wall to hit against, keep practicing and you'll start to get the feel of the ball first, pick a grip stick with it (Don't change your grip unless it is hurting you or it is absolutely necessary for other reasons). You make sure every time you swing you hit the ball at least (paying $70/hour and every time he feeds you the ball you swing and miss is totally not going to do it for you). Get the tennis channel it is $4.95 a month and have a lot of tips to offer as well as tennis magazine for $12 a year.
If you are serious about picking up the sport, I'll keep with the wall and another partner (preferably better player than you are) for maybe a year to 2. Then I would start to pay money for lessons. My point is, there are a lot of basics you can learn for free before you need someone to direct you.
My other advice, don't feel bad or give up because you are not so good at first. It is a hard to sport to learned at later ages, but it feels a damn good when you blast a winner by your opponent (you will know then it came from all the year of practice...lol)
Let me know if you have more questions.
Good Luck!