You should work on a task like you are enjoying the task. Complete the task as if it is your own task. The more interest you show in the task the more it becomes easier and quality of the task is certainly improved. Clients prefer those freelancers who focus on details of the project and show deep interest in what they are doing.
Time is important, in fact the most important thing in every project. A good freelancer makes a correct estimate of the time required to complete the task and then completes the task within agreed time period in any case. You should also try to make a realistic estimate regarding the time required to complete the task. Break the project down into small modules and make an estimate for the time required to complete the module and then add up these times to get an estimate of the total time. Also add some time as a buffer, but once you have agreed upon the time, you should meet the deadline in any case.
Ask for Feedback and Rating
As aforementioned, portfolio and feedback are the two things that are reviewed by the client before he awards a job. A good feedback means, you have done the job well and when a new client reviews your portfolio, if he sees good feedbacks and ratings your chances of getting hired increase instantly. Therefore after completing a job, you should ask your client to leave feedback on your work and also rate your work.
These are the 7 things that every successful freelancer do and if you want to become a good freelancer you should also try to implement these strategies in your freelancing career, you will soon see the difference in the amount of money and jobs coming towards you.