How do you sell yourself to an employer when you have been out of work for so long?

Ok so I have been out of work for a year and a hlaf- main reason being I can not find work- and when I do and get an interview- I am not successful. I have only just started volunteering- for various reasons- not because I am lazy lol! But nobody seems interested in me- even though I try to sell myself more on the application form/CV by saying I have started volunteering. I couldn't face going to a few of my interviews that i was offered last year- it was so close after my gran had pes away- that my feelings just overtook me- plus- i also have confidence issues- in that when I get an interview for a job that I am least expecting- and is something I actually want- I accept it- but then sometimes get to the day of the interview and I can feel so anxious about it- i think because subconciously I do not feel good enough- so the feeling s just come on. Its not that I do not have the capabilities- its just my subconcious overrides. How can I get more interviews, when no one is interested- how can i sell myself more- I only have experience in customer service- contact centres/ retail and a bit of telephone fundraising- so there is not alot I can apply for. Plus I can not stand working in contact centres- its not for me at all. I want someone to give me a chance but no one will- and the longer this goes on- the more I'm worried that the chances of me getting a job will go down and down. help please ta..