Know your style:
The first thing you must do is to evaluate yourself and find out what your actual style is. Do not try to do everything rather it is better to stick with your natural ability. That is what you can do well. However, if you have that panache to work in several styles then polish up your skills before doing it.
Produce work of professional level:
If you want to make illustration your career then it is better to do it with complete dedication. Improve your understanding of content and then produce work at a level which is not easy to ignore. Do not waste publishers’ time by sending them your amateur and immature pieces of work.
You should ensure that people can contact you easily. The traditional way is to send your contact information, phone numbers and postal address, with your work. However, internet has revolutionised this field as now you can make your own website and make your best work available to view. You can also find many business websites providing all the professionals a proper platform.
If someone trusts you then you should make that person feel that it was a right decision. No matter how big or small the project is, you should be professional and deliver your art work well in time. If your client wants you to rework then you should cooperate and modify your piece of art.
Formulate a contract:
It is always better to get everything in writing to avoid any unforeseen trouble. It is not necessary that your client also understands the art work so you should sign a contract in which everything is clearly mentioned.
Ask full price:
Do not undersell yourself ever rather you should ask full price of your work. However, be honest and courteous while negotiating.