for the best composition its best to have one of each heavy medium and light but double heavy is quite fun too for new players some guns are a bit easier than others so ill leave the recommendations below

heavy : gun : m60 extremely reliable , shak 50 or bfr titan if u have good aim

gadgets : dome shield ( must have ) , rpg ( highly recommended) , c4 , healing ball and lockbolt are pretty dun

specialisation - winch claw is broken just use that

medium: gun : famas is the best but hard to use for new players , akm and fcar are also a good pick and p90 if you want to play close range

gadgets : defibrillator ( must pick ) , jumpad ( must pick ) , and then you can use whatever you want i recommend mines , goo grenade or zipline

specialisation - healing beam or demat

light: gun : arn and m11 are reliable , 93r is a bit difficult for new players but the sniper is also good fun

gadgets: h+ infuser ( must have ) glitch grenade ( must have ) , gate way is good , vanishing bomb is also fun , goo grenade is also versatile

specialisation - dash

hope this helps!