Every tribe is strong if played correctly and most people would even consider Gauls to be the strongest and they are the easiest to play, so for someone who is new it's the best choice.
Here are a few tips:
Use the quest book, the resources from it especially allow you to build up your village quickly.
Also, there is a quest that will give you 800 culture points for building the townhall (The first feast will give another 500 cp), this way you can get your scond village quickly.
My building order would be the following, but im sure there are also other paths:
- resource fields up to 5 , crop fields up to 5
- residence 5 (you get an upgrade to level 10 from the questbook for free!)
- build 3 settlers, this will give you resources from the questbook again
- Mainbuilding lvl 10, academy lvl 10 -> townhall + second village.
If you get a 15c as second village, I recommend you to build up the resource fields to level 10 (12 if you make it a city later) because you will complete the "all resource fields to level 10" quest with that, because well, in that village they all are lvl 10
Also dont worry if some quests do not show up in the questbook, they sometimes are hidden until you complete other quests before, but they are still there!