I have two mates I've convinced to try EU4, and obviously the depth and complexity of the game is pretty daunting. We're gonna play for a few hours together (probably as one nation) just so I can show them some of the basics.

Obviously, time is the best teacher and the longer the play the better they will get, but I fear they don't have the inclination to sit down and watch a Let's Play (which is how I learnt), so I was just wondering how you thought the best way to go about it was.

Would it be better to go the colonising/New World route (Spain, Portugal, Great Britain) or the more European warfare/HRE/reformation route (Austria, Italian Minor, Poland, etc.) or in between (France) to learn the most without being overwhelmed?

What are some essential things you need to know? Obviously things like manpower, Casus Belli, alliances, force-limits and attrition, etc. are essential, but what about Personal Unions (i.e. does that deserve an in depth explanation on a first playthrough?) How in depth should I go into trade? etc.

What are some invaluable tips I can pass on to my friends? (my personal number 1 is 'just because you lose a war doesn't mean the game is over; learn from your mistakes')

Cheers for any help you can give.