I just bumped into this topic by chance.

It's sad/funny how someone asks how to up their rating on BitBargain and the two replies are "use another marketplace" and "you must be talking about BitcoinTalk instead of BitBargain".

Detailed help to achieve a higher score is here: https://bitbargain.co.uk/bitrating

Recommended steps:

1) verify phone number (giving you a 53 rating, more than the default one)
2) make at least one trade (after that, your score keeps going up for a while as time goes by)
3) complete ID verification if you can / don't mind (that will boost the score)