If you're going to make volunteering work for you as a route to building your skills and confidence for paid work, you have to go about it the right way.
First, think carefully about what kind of paid work you're looking for - what area do you want to work in? What sort of work do you want to do? Then ask yourself what's stopping you from getting that job - what skills, qualities or experiences are missing?
It's helpful to look at job ads and specifications for similar jobs to find out what employers are asking for. Then plan how volunteering can help you to develop your qualities and skills that will enable you to fill the gaps and become a more interesting candidate for a paid job.
Think creatively, but be realistic! If you want to work in retail but don't have any experience, volunteering in your local charity shop would be a useful step forward. However, if you're trying to get a promotion to a managerial job, it might not help unless you enter into a role in managing a team or a project for an organisation. What might do is volunteering in a role as school governor, or trustee for a charity, to build and demonstrate your management skills.
Be selective, decide what you want and look for a volunteering opportunity that can match your expectations.
Because you want to get something specific from volunteering, you might want to look for an organisation that can give you:
Be prepared not to get everything you want from one volunteering opportunity. You might need to volunteer with different organisations and do more than one type of volunteering to get the opportunity to build the skills, qualities and experience you need. Think about what time scale you want to volunteer for; you may find that volunteering for a specific project or period of time works better for you than on-going longer term volunteering.
If you want to volunteer to develop your skills, qualities and career, treat it as a beneficial activity, make a commitment to your volunteering and enjoy it.