This seems obvious but players tend to enjoy playing as a lone-wolf. When you move from area to area, stick together in case of an ambush. If someone needs to heal, teammates can build around them and provide cover. When you’re building a base, build together in order to speed up the process. Never attack a team by yourself. If your solo attack goes awry, you’ll almost certainly be downed and finished off before your teammates can get to you.
In Duos, look for a team who has split up. Take out each enemy individually to outnumber them each fight.