suggestion for beginner

I have no clue on which region to focus first

what do you suggest ?

Who knows.. There will be a bunch of changes today, even systematic ones so we really can't tell. 

Haven't played the game yet but from what I saw (at least for champions) regions seems to have some consistency on a couple of given theme. Might be wrong I count a bit on my CCG experience from previous games.

Noxus for example seems dedicated to aggression and/or fast decks. Piltover & Zaun looks rather comboish/spell based and winning through constant nexus damage from spells and champions effect. Freljord looks definitely control oriented so for slower decks. Demacia looks heavily based on board presence regardless of your strategy (even Fiona which looks very controlish is based on trading enemies), with the exception of Lux which looks rather spell focused. Shadow Isles seems based on board generation on a general manner and oppressive plays (through fearsome).

I have an harder time classing Ionia, they look more diverse, the jack of all trade kind. Zed is pure aggro, Shen looks midrange/control, Karma is ramp/control and Yasuo is... no clue, midrange/combo maybe ?

I used those impression to decide my starting factions (Ionia/Freljord), maybe you could just consider the champions and decide which kind you like?

As noted on the news post (in more detail) - I personally recommend SI if you like to play aggro decks, Freljord if you like control decks, and Demacia if you want to sit on the fence.

Tell us what kinds of decks you like in other games, and it will be easier to make a recommendation.

Or maybe watch some videos of the pre-beta event that streamers got to play about a month ago. The cards will be seeing some balance tweaks, but the overall flavor of each region should remain pretty much the same.

OR read up on individual Champion cards. Pick a few you like and focus on those regions. (Or focus on the single region that has the most Champs you enjoy.)

I always recommend new players (Which are new to CCG, We all are new to Runeterra after all) to level your regions up for at least 5 and jump to another.

Yes, you can change your regional rewards whenever you want and if i remember correct all of their level 4 reward is a Champion Wildcard, which it will help you complete a deck probably after you leveled 6 regions to 5.

You would collect lots of commons and rares too probably with this way. So, instead of following only one region to its best reward, cycle it.

Also, Region rewards are not limited as well. After you complete, it will still reward you so cycling seems best option for progressing.

thanks a lot for all suggestions

I will start with Noxus which seems good to make lost of matches in lesser time and when I have reached level 5 I will switch