I will commend you for practicing and having the motivation to become a professional calligrapher. Itís a nice way to make money and meet people. (That is if you donít just sit at home and address envelopes and never mix with the calligraphy community!) Iím sure there are people out there that are capable of learning to do calligraphy (from a book) well enough for their own enjoyment, but I doubt that you can be called a professional calligrapher without some kind of tutoring from a teacher. Especially, in the market today. Professional calligraphy has some pretty high standards any more. There are so many people who are exellent calligraphers and you would want to measure up to some degree to the standards set.
Most outside people donít know the difference between ďgoodĒ and ďpoorĒ calligraphy, but as a craftsman you should be the best you can be. At the very least you should take a class or private lessons with a good teacher to ask them if youíre good enough to get paid for the services. You wouldnít want to be known for the poor quality of your work would you? Itís a good idea to do some ďfreeĒ work for friends and relatives and see how they respond. But, when you decide to work professionally you need to find out the going rate and charge the same rate. If you charge less because youíre a beginner, itís not fair to the market and the people who rely on this work for a living, it brings down the price to everyone. It will no doubt take you longer to do the work than a seasoned calligrapher, so you wonít be getting paid as much in that sense. Please, donít give discounts on addressing envelopes. Show the client your work and see if they are happy with the work so they will know the quality. Then charge the going rate, which here in LA is $2-$4 per envelope. Usually a 3 or 4 line address. Itís helpful to say that extra lines are extra cost. Iíve been stuck doing 6 lines envelopes for the price of 3 lines because I didnít make that distinction. Sometimes itís helpful to say there is a set-up charge for color matching or other incidentals, like the envelope is a nightmare to write on! Just because they chose terrible envelopes doesnít mean that you should charge the same as easy envelopes. That alone can double the time it takes to complete the job. This will also teach you to tell the client that you canít give them a final extimate till you write on the envelopes. Giving a quote over the phone when you donít know the type of names and the type of envelopes usually ends with a headache! (Ask me how I know this!!)
There are many teachers that will review your work and tell you what you need to work on to improve the quality and they can probably give you some hints and tips that will make the job easier. So my advice is to set aside some time and get some lessons to get you to the level needed for professional work.