The most common and easiest to describe of these brutal tactics was simply razing whole villages to the ground when the residents were slaughtered. First and foremost, Vikings simply wanted loot; if the hassle of attacking a settlement or town wasn’t worth the amount of loot they could potentially get, they wouldn’t go. If you struck a deal with them, they MAY leave you in peace, but it’s just as likely they’d just kill you for any valuables you may be hiding or not being forthright with. If they chose the former, they’d simply return and either get more loot from you, kill you, or bring you under Danelaw.
You of course had slavery, as well, which was incredibly common for Vikings to seek.
From what I know, things such as the “Viking angel” are completely apocryphal and were never used.