Experience managing office administration tasks, good typing skills, etc are the important skills you need. Employers look for reasonable levels of experience like GCSEs including English. It can be helpful if you have passed secretarial courses of some kind. There are many of such courses available.

Your experience managing computer systems and running a business can be extremely helpful. You will also need audio transcription skills – that is to type the matters recorded in tapes or audio files.

You can also undergo further training while on the job. There are certificate programs, diploma courses, etc for legal secretaries offered by organizations like Institute of Legal Executives, Institute of Legal Secretaries, etc. Additional qualifications can help you get promoted to higher posts and bigger salaries.