Well yes the Vikings loved trade, but had troubles trading with Christians, as Christendom increasingly operated like a trade union a la E.U. They made it difficult for fair trade for the pagans, pushing them to resort to more raiding.
But some "traders" were quite creative, as Scandinavians dont have a ton of resources back home, so they could raid one place and then sail around trading their looted goods even in the same country.
Also the Vikings in war used a lot of psychological warfare, sometimes they would kill all but one in a village so that the survivor would run and tell the tale to the neighboring villages.
What happened then? Well, the vikings didnt have to kill or raid the neighbours at all, they were too afraid and gave what they had willingly.
Viking raids operated like commandos, they were well trained, motivated and equipped. They had training before going west, to England, France, Ireland and Iberia, using the baltics and Finland often as training grounds for younger crews.
One important detail though, the Norsemen(A.k.a Nordmenn, a.k.a Normans, a.k.a Norwegians), Danes and Swedes didnt stop with their warrior traditions on the first day of Christendom(After conversion).
THE FIRST CRUSADER KING, was the Norwegian King Sigurd I "Jorsalfar"(Jerusalem traveller), the Crusader, Magnusson (1089-1130).
He led the Norwegian crusade, using longboats. He wintered in England before travelling down the Portuguese-Moorish coast, raiding Lisbon to liberate Chrsitians, but couldnt see the difference between Muslims and Christians, killing and looting both sides(Mistakes where made).
His forces kept on sailing south until the straits of Gibraltar when they ships got stuck due to no wind.
When they saw a Muslim fleet approaching them they according to the story, celebrated happy because they were saved, thinking that they only had to defeat the enemy and use their ships to help their own out of the situation.
They won, and the travels continued raiding Iberia, Belearics and continuing to Sicily where they where welcomed by Roger II, a Norman.
Then he went to the Levant, Acre, and Jerusalem, aiding in the crusades, having a good time with Baldwin, helping him here and there etc.
Lastly, when it was time to return home Sigurd travelled to Constantinople with his fleet, where according to sagas "King Sigurd approached Miklagard(Constantinople), a city so tall, majestic that it swallowed his army whole". The Saga continues to describe the Byzantine Emperors perspective "The fleet was so large, that it was like if a giant dragon approached our dear city" (Something along those lines, its from memory).
He then left most of his army, and all his ships as gift to Emperor Alexios, beefing up the Varangian guard. He stayed for a while before getting horses to treasuries to bring back home to Norway.
Most of his men stayed in the varangian, but they returned slowly, richer and more experienced than ever before.
So, they werent under par I would say.
