Haha, my biggest 'Key Point' is time
Having to take out 7 or 9 other opponents is just too time consuming. If you're 10+ tech ahead then you can line up artillery, rocket artillery, and all the fun tricks to decimate an opponent... bu then you have to march forever to get anywhere. RR isn't that fast, and Naval flotillas take forever.
I just can't do the micro.
But yes, my advice is go tech-focused as long as possible to generate a massive tech lead and then go for 'head shots' with focused groups of advanced units.
I just had a terrible game as Russia. Small pangea quick low sealevel.
There were following enemies: Greece, Assyria, Korea, Germany and England.
Basically I started in the middle of the map. Which is both good and bad. Sadly, there was very little defensible locations to the west of me.
I managed to forward settle against Germany, with two cities, and even captured GErmany's liberty settler. This forward settle in the west, was actually in good location in a mountain pass, which made for good defensive location. I also settled my fourth expand city into mt.kilimanjaro.
At this point Greece and Germany were behind the mountain pass in the west, but Assyria was behind jungle in the north, and England was in the east behind some hills.
Korea was totally isolated in some peninsula for the entire game. I was backstabbed by Assyria, but I took out his second city with x-bows and horsemen. Then, I citadel-bombed his luxuries after peace, for good measure, so now he only had one lux remaining, LOL.
AT this point England attacked me with longbows, but knights and xbows took Lizzy out easily.
Then I tried to destroy Greece with a couple unsuccessful attack wars.Greece had tons of bad cities cluttered together with massive unit spam. I had cossack and arty push into Greece but only raized down his border city in front of my mountain pass. Then he offered me some lux and gold.
I went autocracy and took Germanys capital easily. Then I tried to push into Greece from a wider frontage, with tanks, cossacks, artillery, gatlings and bombers. I started getting HUGE unhappiness from Korea's tourism. I had 4 barbarian tanks in my capital because of unhappiness.
Then I figured out that I could quickly get rid of that unhapiness If I simply give to Bismarck, some of these crappy Greek captured cities. That way, he gets a free city, because he's not getting his capital Berlin back any time soon... He can also decide if he weants to raze it or keep it
This tactic worked perfectly and I only kept a straight line, of cities, into Greece's capital as puppets.
Then I rushbought some nukes, bought some carriers, and finished off Korea with modern armors. The game took bloody long to finish because I never had access to many city states in early game, only 2 CS allies, And greece and Korea simply took most of the city states as their allies. My happiness sucked a little bit even though I was fricking autocracy!!!
I did have sistine chapel, and some early wonders though. Bismarck got alhambra but I took it from him. It feels sometimes really hard to fight back vs enemy tourism. Korea was freedom ideology, but there was not world ideology yet.