To be successful in freelancing, you need to develop a wide range of skills that are not only related to your specific field of expertise but also essential for managing your freelance business effectively. Below are some key skills you should consider developing:

1. Technical Skills:
  - Depending on your freelancing niche, you need to have a strong command of the technical skills required to perform your work. For example, if you are a web developer, you should be proficient in programming languages like HTML, CSS, JavaScript, etc. If you are a graphic designer, you should be skilled in using design software like Adobe Photoshop or Illustrator.

2. Communication Skills:
  - Effective communication is crucial to freelancing success. You need to be able to clearly communicate your ideas, requirements, and expectations with clients. Additionally, active listening skills are important to understand client needs and provide appropriate solutions. Strong written communication skills are also essential for writing proposals, emails, and other forms of client communication.

3. Time Management:
  - As a freelancer, you are responsible for managing your own time and meeting deadlines. Developing good time management skills will help you stay organized, prioritize tasks, and deliver projects on time. Utilize tools like project management software or time-tracking apps to help you stay on track.

4. Marketing and Self-Promotion:
  - Freelancers need to market themselves and their services to attract clients. Learn how to create a compelling portfolio or website to showcase your work. Understand the basics of search engine optimization (SEO) to improve your online visibility. Networking and building relationships with potential clients through platforms like LinkedIn or attending industry events can also be beneficial.

5. Negotiation and Pricing:
  - Being able to negotiate fair rates and pricing for your services is important to maintain profitability. Learn how to effectively negotiate with clients, set your rates based on market value, and understand the value you bring to the table. Additionally, understanding contracts and legal aspects of freelancing can help protect your rights and interests.

6. Problem-Solving and Adaptability:
  - Freelancers often face unique challenges and unexpected situations. Developing problem-solving skills and being adaptable will help you overcome obstacles and find solutions. Being open to learning new technologies or adapting to changing client requirements can give you a competitive edge.

7. Financial Management:
  - Freelancers need to handle their finances effectively. Learn basic financial management skills such as budgeting, invoicing, and tracking expenses. Familiarize yourself with accounting software or tools that can help streamline your financial processes.

References:
- Freelancer.com's "Top Skills for Freelancers": https://www.freelancer.com/community/articles/top-skills-for-freelancers
- Upwork's "10 Skills You Need to Succeed on Upwork": https://www.upwork.com/resources/skills-you-need-to-succeed-on-upwork