You need to have a good standard of English grammar and enjoy reading. With this you can set up almost anywhere, in your bedroom, living room or somewhere that has a little space as editorial work will need this, especially if you're working on a large job.
Working at home means trying to keep home and work separate, this is difficult especially is you have children. You should be in control and make provisions to separate the vocation of work and home as they do not mix well.
You will be in full control of your financial destiny, Perhaps having been employee or in full time education before this will be a complete change as you have to manage on my own. The job can be very lonely. The need for concentration for long periods in complete silence are normal in this job.
You will need a little capital to start up this business, to get the correct training and software tools. It's not a lot but you still need to invest in order to give a professional service to clients.
Proofreading is of course the process of checking books, magazines and journals for errors before they become published. It is an vital job which carries an imperative degree of responsibility. Proper training through a recognised proofreading course is therefore essential if you are to succeed. A course that has a certificate of accreditation will give you more work and your clients peace of mine and confidence to use you.
There are many places yo can go for training, many online. listed here are a few specialist course that you may enquire about. Some with a money back guarantee if you feel that this is not for you.
If you think this may be for you at this stage, there is a test yo can take to judge for yourself how you fare
A selection of sites offering courses:
http://www.train4publishing.co.uk/ - A high quality training offered in the UK and overseas.
http://www.interactivetraining.co.uk/ - Online training and many tips given here
http://www.interactivetraining.co.uk/ - A one day effective training course offered here
http://www.chapterhousepublishing.co.uk/ - Offers a variety of courses that may suit you
There are countless publications that come under the 'teach yourself' category. Which are good and which are bad is not know until you have purchased. It is very much a lottery in this genre. It is worth just buying hardback learning material that you can preview, this of course is still not a 100% guarantee that the rest of the book lives up to the first part. Don't forget the publishers of these books are a business to sell, not flood the market with new proofreading/copy-editor recruits.
Logging all your hours in a log book or desk diary helps with invoicing and a guide to calculate how much I've earned each day. Organisation is always the key with all aspects of this job.
You need to try this out before giving up any day job. start off slowly, you will know whether it is for you pretty quickly. But before you start, ask yourself; Do you like working under you own steam? How motivated and self-reliant are you? Finally, always remember there's no one to turn to if it you have problems, just yourself.