Even when redemption starts you will not be asked to enter your btt credentials anywhere.
A detailed guide on how to get your NEM will be released soon but there are some things that you can count on to avoid scams:

When redemption starts you will most likely get a pm from me.
You won't need to enter any username or password anywhere.
We're going to use https
There will  be a detailed announcement so before you hear anything official on all channels redemption hasn't started yet.   

Also if you've already fallen for a scam. TELL ME NOW ! Most likely scenario is that the scammers will request assets.

Seeing this do you guys think we should stop issueing assets to avoid scammers requesting assets from legit accounts ?