Both IEEE and ACM have good reputations. Set long-term goals for your freelancing business. Freelancers with no desire to go full-time can use less grandiose goals. Customer Management Keeping your customers happy will ensure they pay you for current work, hire you again, and recommend you to their friends. When you are at the customer site, always remember that you are a guest.
High expectations are the leading cause of disappointment.
Managing customers' and your own expectations is an important skill for all contractors. Customer expectations are tricky. You must sell yourself well enough to get the job, but not so well that the client has unrealistic expectations of your abilities. Be sure to represent your skills accurately. Make the best time estimates you can on the job for which you're hired.