Allot depends on how aggressive your start but basically you look at what armies you have, what armies you need, what threats surround you and then start by figuring where to best have an aircraft factory, barracks, tank plants and get those built since they are fast builds and level ones should do you fine until you get up to level three and four research.
If you have a tank focus you could build a couple tank plants but no sense building a bunch of different army producing buildings in one city. Moving between cities is easier.
At the same time you need to get the Industry going no matter what your style. The five 1500 resource point provinces are the best bang for the buck developing so you could get those started while you consider adding to the cities maybe propaganda offices or recruitment centers. And this is only for the 6000 resource point cities, the 3000 point cities are not efficient to develop early but are good for army production. Oh my god this could be a long answer!
Quickly on Industry.
Get an idea what resources are most needed by you. If airplanes you make rare materials priority or artillery would make Goods a priority. Usually at the start you have two or three resources that you need more then the others due to style.
Build the level 1 & 2 industries on the provinces on your most precious resource provinces. If it's the first day and that resource is bordering a potential adversary maybe the city resource is better to start on. Hate to invest and have province steam rolled the next day. Start level 3 on those province and start level 1 going on the less precious and get those to 2 and 3 as you start to develop the precious ones in the cities.
I just suggest that order because the level 3 is the best bang for the buck. Level 1 & 2 together cost about $7500 plus equivalent in Metal, Oil and Rare Material, takes 22 hrs and give back $1500 per day while level 3 costs $5650, takes 20 hrs and also gives back $1500.
The provinces are slightly better then cities since a province level 3 adds 3000 resource points while a city level 3 adds 2700. The level 4 cost $7500, takes 26 hrs and gives back $1500. Level 5 costs $10K, takes 32 hrs and gives back $1800.
The level 5 is still a much better investment then building level threes in the 3000 point resource cities or the 750 point resource provinces or captured territory. So by the time you spent all the money and resources to for the above upgrades you will be in the thick of battle and will need all your resources toward that end I think.
On the Propaganda offices and recruitment centers.
If you are finding in your games that lack of man power is stopping your production plans it not a bad idea to build recruitment centers in your five 6000 point cities as they are also your highest man power cities. ( Open Province Administration and sort by manpower. ) Costly in food and goods to get them all to level three, but you are busy spending the metal, oil and rare material on industry so unless you making a massive infantry army then why not. Build all five cities to level three will nab an extra 6000 manpower a day which come day 20 it might be really handy to have that 100K extra manpower if you're mass producing leveled up armies or upgrading. That might not be a problem depending on your style.
Propaganda office are only half the cost and will bring the moral up quicker which adds a little speed and resource production. Instead of taking five days to get to 100% moral it might only take three days or something. Taking a capital is better since that increases every province and city by 10%. But still it's not a bad investment, pays for itself at least and three weeks into the game when expansion is killing your moral you will have to build them anyway.
Fortifications and Infrastructure.
Kind of expensive to start but depending on the battle map. Infrastructure to speed travel between two control points, fortifications to protect armies that are not going to move. Adds hit points to cities maybe keeping a precious aircraft factory healthy while other buildings get beat down. I don't know.
Anyway. Not good to be spending resources on level 2 and 3 tank plants that are not needed when there is still industry to be built.
