Naturally it depends on what you are writing the bio for - to get a publishing deal, a showcase gig, etc. In my humble opinon, a bio which does not have "third party" evidence to substantiate - means nothing. A bio needs to include newpaper articles, press releases, etc. to actually impress anyone in the industry.
Naturally for a new writer with little or no track record - there may be nothing available. I will now share slightly deceptive, but reasonably effective ways to achive "third party evidence".
If you have local community newpapers (or "underground" entertainment newspapers) - pay to take out an add, as an example - mjr releases newest CD at CD release party on 3/30/07. Over 200 people crammed the ABC club to see mjr perform songs from his recent independant release on mjr records After the performance, at least 30 people stood in line to purchase the CD and have mjr sign pictures and tee shirts...blah blah blah. If you are paying for an add, perhaps you can even get a "reporter" from the rag to conduct an interview and reference your small but well equiped recording studio and include some quotes.
Or, print a few flyers (nartually in different colors and fonts) advertising various gigs in which mjr will open for the XYZ band (playing his original material..... blah, blah) at the ABC club (or even better - mjr will headline ABC club).
Naturally, actual achievments (in which you can claim your material appeared in x film on on x artist's CD - or even if you really headlined ABC club) is better. But if you can't dazzle with brilliance....baffle with bullshit.
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