Shall I start my own company or improve my skills first?

I am self employed and I work in public relations. I have been working in the same company 'freelance' (5 days a week) for 3 years. My boss has suggested I gain experience elsewhere to build my profile in the industry. He wont actually employ me as he doesn't employ anyone!

I have always wanted to set up my own public relations company however always been discouraged by work colleagues who sometimes make me feel I am not quite good enough yet. Which could be the case, I am still fairly new to the industry. I do understand some of skills need to be more practised e.g writing.

I always read stories of self made people who start up business straight out of school and learn 'on the job' who have made quite a decent living for themselves.

I am worried to make the jump or to do it alongside where I am working now and cutting my days down to 3 a week however I was just wondering what an outside perspective would be on the situation!

Or do I just find another industry job and get employed by a different company?

Thanks!