look under Strategy Discussion: Beginner Tips for Playing Better.
There are other posts also if you search around.
Very generally, I would advise:
Get a country that has some borders you don't have to defend right away (coastline or edge of map)
Attack a country nearby if you can get a quick win (often a small AI country), otherwise work on economy and watch what others are doing.
DO join an alliance IF it's not with some faraway countries that won't be able to help you. In any case, work some deals with other countries.
Resources: build level II workshops, RRs, and factories in double resource provinces. Also harbors if possible. Build some barracks to help. The posts I see advise you do these also in double resource provinces since you get more infantry that way. RRs give you the biggest resource boost.
Play with the resources to stock up on the resources you will need. Sure, it's nice to have everything positive, but sometimes you want to maximize certain resources (usually something in energy).
Use your heroes when they become available.
Always protect your attacking artillery with a group of infantry or other troops in front of it, to block it from being overrun.
As you play more and more, you will get a feel for when to attack and when to defend. I'm still working on that part.
