I agree with tutti flutti. I have been participating in folk music for a fairly short time (as opposed to listening which I have been doing for a lot longer) and I have found that people have been very encouraging of my efforts.

I find sessions (everyone playing together) and singarounds both have their value. Sessions are great for getting into playing together, learning tunes and developing listening skills. Singarounds put you on your mettle as you are on your own. I have had my share of disasters, but but people are generally very supportive and if you keep trying, you definitely improve. One thing in particular I find singarounds good for is learning to deal with mistakes. You are inevitably going to make mistakes, forget words/tunes etc. and how you deal with them is more important than the fact you make them, IMO. That does not mean you should not try to reduce the number of mistakes you make, but remember even seasoned professionals make mistakes from time to time.