Bio-oil is expensive and won't work for everybody. Cocoa butter is cheaper, but again won't work for everybody. It depends on the type of scaring and how old they are etc. If the scars are particularly red or raised, you can get a teroid-based cream from your GP which you apply twice a day that will thin the scar/reduce the colour. If you don't want your GP to know, you could say that your 'issues' are in the past etc.
You could wear tubi-grip and say that you're suffering from Repetitive Strain Injury.
If you live in the UK, Primark sell long-sleeved thin tshirts which are really useful :)
Aslo, check out
This Thread for more tips (: