How much work should I do for free to gain experience?

How much work should I do for free on the promise of future work?  How will I know if I'm getting taken advantage of and how do I put my foot down?

Doing work for free is being taken advantage of.  You might not get paid in money - maybe you do a swap or barter.  But a promise isn't payment.

But I am still a beginner and isn’t any work useful experience ? Even if you’re not feeling good about it?

So charge accordingly.  We'll do a taster project to see if we can work together - this tiny piece of the finished thing for a small fee.  If they won't even pay that then they're out to screw you.  

But I need the experience?

What sort of experience do you need?  A cheap client is a bad client and all you'll gain are bad experiences.  You want a good client so you've got something worthwhile to show at the end of it - and good clients pay.  

And finally, I have a client research process; really simple and it takes just a few minutes each day.  So you can make yourself irresistible to the good clients, raise your prices and leave the bad clients scrambling in the dirt.  Hit reply to find out more.