The Norse culture in Scandinavia was heavily based around the virtue of honour, and warfare was undoubtedly one of their most prestigious activities. Thus all free men were expected to own a weapon (and even encouraged to carry them around), although their weapons and armour depended a lot on their wealth. When we think about your average farmer/part-time viking raider, he would probably own a spear, which was typical amongst the lower classes, accompanied with a shield. Other possible weapons were axes (pretty common) or the "sax" (a dagger-like sword/knife of sorts). Proper one-handed swords were more used by the wealthier Norsemen, and they'd often ornament them in order to display their status. You probably wouldn't see too many "average" viking raiders using swords.

Your average raider would not be wearing a helmet–at least not a viking helmet–but might have worn a four-on-one mail, which were less expensive and less cumbersome than a proper mail. Mail in general was pretty expensive and hard to come by in early medieval Europe, so it's unknown as to how commonplace they really were. There have also been found lammelar armour in Sweden during archaeological excavations, which could be evidence that some Norse warriors wore them, but this is debatable. The armour the vikings wore is still controversial, and it's very likely that many of them simply wore ordinary clothing, tunics, or light protection made out of linen, wool, et cetera, with only the shield as their means of defense. It's also worth noting that foreign weapons and armour circulated among them after raids or through trade, so it's not unlikely that some raiders could have been seen sporting Frankish gear, and so forth. In Heimskringla (the Olav Haraldsson's saga in case you're interested) it is for example written: "One hundred Vikings appeared in coats of ring-mail, wearing foreign helmets," during a battle in the early 1000s. Of course, most stuff from the sagas are to be taken with a grain of salt, but wearing foreign armour was definitely not unheard of.

Not a super in-depth answer, but I hope that provides a rough image. :)