You can advertise for clients. That might be more or less appropriate depending on which area you are in. In most places there will be some kind of new age or alternative therapy advertising going on already and you would fit right in. In many areas there are local new age or holistic magazines that could be useful.
Regular newspapers or phone books are fine too. You just have to be more careful what you position yourself as. You would not want to step too much into the turn of psychologists or psychiatrists. If you pick anything with a "Spiritual" in front of it, you are probably fine. If you are under "Spiritual Guidance" or something like that, nobody will have a problem with that.
The best approach to advertising is to list problems, not solutions. Don't say that you can make people happy and successful. List things that the person can identify with as being wrong with her. Depression, career blocks, relationship issues, nervousness, unexplained failures, etc. List some things that a potential client can identify with and say "Yes, that is me, this guy understands me!" You don't have to say what you are going to do about those things, you just have to indicate that you know about them.
The word "Clearing" works quite well in advertising. People are likely to come in and say that they "want some of that", even if you haven't explained yet what you do.
When people search out a counselor, they usually like some kind of personal feel to the ad. If it has your name and your picture, they feel that they know you. Also, attaching their trust to you rather than to a style of technique or to an organization will keep things more simple.
The very best way of getting clients is by referrals from existing satisfied clients. However, you can't necessarily start out like that. Well, you could go and process a bunch of people for free, and then they would send in their friends, that is a possibility. But usually you will have to do some kind of marketing to get started and build up a clientele and/or a reputation.
It would be very useful if you could set up a relationship with some kind of well-established health practitioner, a doctor or chiropractor. It will usually be a holistic practitioner who would be open to sending clients to you, but any professional would work, really. If you can get one holistic clinic to refer those of their patients who could use some mental/emotional work to supplement their physical work, well, then you will probably have plenty of clients. Often it will then be appropriate to see the clients in the office of that center, and actually that makes everything work better. The patients will just regard you as another professional practitioner and they won't give much thought to the legitimacy of what you do.
You can also go to holistic expos, psychic faires, or other appropriate gatherings of many people who are interested in change. You can rent a booth and set yourself up doing demonstration sessions. Finding positive moments in past lives works great for that. You can usually charge for it, or you can do it free just to attract people. This is also a great way of quickly building up a mailing list.
If you have a mailing list you can send out direct mailings. It depends on the area how well it will work. It the US it takes quite a lot of mailed fliers to get responses. But you can do it in various ways. You can write little informative articles and send out, and set yourself up as a credible expert on life. You can make special introductory offers, send out coupons for a 1/2 off first session, and so forth.
If you do have a mailing list of people who have shown some kind of interest, then you can work it on the phone. You would go through the list once in a while and call the people up who have not explicitly stated that they are not interested. Hear how they are doing, stay in good communication with them. If something comes up that you know you can help them with, indicate that to them. Keep a record of the results of all the phone calls.
There are many ways of speeding up the inflow of clients. However, the main way you get clients is simply by doing good processing. If you do it and you do it well, more people will come in. It is not necessarily those exact same people you had in session who will bring in the next people. It is more that outflow will give inflow. If you output some improved people then you will get more in who need it.
A lack of paying clients is not in itself any excuse for not doing sessions. That can be a catch-22. You need some clients to start with to make some satisfied customers who will bring in more customers. So, with the first clients, don't worry about where they come from or what they pay. Just get some people and put them in session. Use your friends, your family, pick up some people on the street, or just go to coffee shops or bars and talk to people while using your transformational processing principles.
Print up a business card that says that you are a Process Facilitator or a Clearing Practitioner, or whatever you want to be called. Give it to people you meet. Tell them that you do processing or that you do change work. You don't have to sell yourself much, just tell them that you are there. Also make some brochures, if people want to know more. Just a few pages telling what might be addressed with processing.