simplest tip i can give you... learn what works best for the 4 elements and the human tendencies that relate to them.
mountain is countered by predator for example due to many players stacking defense or high health regen champs like vlad. so just get a warwick with anti healing auto attacks. you wont win often times due to rng, but it's your best bet for getting a decent placement reliably.
infernal is assassin mage since you can use quiyana. unfortunately this is a slugfest. the people that choose to go warden, predator, mystic, etc. are going to have an easier time getting champs and you basically have to just hope you don't lose your streak.
ocean is a toss up. 30 mana isn't enough to matter and quiyana can still be used for assassin mages, but you'll have an extra ocean instead of extra aoe damage which amounts to very little in the long run since you can't get 4 stacks of ocean without sacrificing your build to compensate for the overabundance of wardens in ocean - if you get a water lux though... it might be worth. in this sort of situation i recommend going for electric glacials to prevent casters from casting and dealing explosive heavy damage to the squishy units.
and cloud. oh boy... this one is garbo. i recommend getting a nasus and hoping. light works well and so does electric. haven't tried much other ones on cloud.
one thing i know is that
shadow, poison, cloud, and mountain are all awful build paths. use them secondary. glacial should always be combined with electric.
focusing on a type of champion is probably the worst thing you can do because what happens is you end up with zero universal buffs and a completely 1 sided attribute focus. for example wardens will give you high defense, but you wont have any magic resist and in most cases damage. mages have massive damage, but in most cases they dont deal well with high damage or crowd control. i'd make a chart to show all the different what beats what, but it'd be ridiculously convoluted.