Can someone in the facility where you work help you with the language or in actually getting the appointment booked? If there is a receptionist who does the booking, they should be working in partnership with you to get the next appointment made.
I have my own office, so it's all up to me. I felt funny about it in the beginning too. I sorta felt like a "salesperson" and that didn't feel comfortable for me. Then, I realized that there is no reason to feel uncomfortable. I believe in massage. I believe in the benefits. I am not telling them anything that is untrue. I will not tell them they have some issues with this or that muscle if it isn't true. Even if they have no particular issues and are just there for stress relief, that is an enormous and necessary benefit these days. So, no need to feel guilty. I began to look at it as making them an offer. It is their option to accept or not. More often than not they will rebook when offered. Some will even thank you for suggesting they rebook before leaving the office, because they know that they will just get distracted and forget to call.
After the massage, when I give them their water I will tell them about any problem areas I may have found or may talk to them about how massage can benefit them with their stress management. Then, there is usually the payment process and after that I will say "So, when would you like to book your next appointment?" That's not a yes or no question. I'm asking for a particular date. That's a bit of a "sales" tactic. Don't ask them if they'd like to make another appointment because they can say no to that. Ask them when and they are more likely to tell you when. If they say they need to check their calendar, give them your card and invite them to give a call when they know their schedule. I will sometimes say "don't wait to long or your muscles will start complaining again and you want to keep them happy so they'll work harder for you."
As for those who say they'd like to get massage but can't afford it. I agree, that they may be fishing for a discount. I'd like to own a Jaguar, but I wouldn't expect the car dealership to lower their prices into my price range. Unfortunately, the truth is that some people will not be able to afford massage. I think letting the know that you offer gift certificates and suggesting they let their loved ones know what they'd like for their birthday/valentine's day, etc. is a great answer!
Sometimes it's just a matter of priorities. I have known clients to give up their regular manicures so they could get more massage. Some people are willing to give up some Starbucks for massage. It's much healthier for you. It costs more to be sick than it does to stay healthy. Unfortunately, people fool themselves into thinking that none of that illness is going to happen to them. They also don't recognize the value that stress management can play in them being healthy. Massage feels good, so how can it possibly also be so good for you? What else feels so good and is good healthy for you? We are conditioned to think that we must be spoiling ourselves or being self-indulgent when we are doing something that feels so good. When we go to the dentist or the gynecologist, we don't seem to feel guilty, but yet those are things that are good for our health. The reason we don't feel guilty is because they don't feel all that great.