To add my own $0.02 ...
I have found WC to actually be easier when taking rather
few provinces in the early game. Generally, the strategery I follow goes like this:
Phase I: 1419 - 1520
The primary goal here is to build up a solid territorial and economic base by conquering all state cultured provinces, at least one port, and at least one CoT. Secondary goals include conquering additional CoT's and gold mines if possible (target those that are not capital provinces), moving DP sliders to maximize the chances of getting a random explorer, reaching Naval 11, reaching Trade 3 and building a fleet of at least 17 ships.
Phase II: 1520 - 1620
By this point, you should be powerful enough to DoW Portugal, then Spain. The goal here is not to actually win something from them (although the CoT in Andalusia is a good target), but to sack their capitals, thereby obtaining their maps. Hit Portugal first, they're usually better explored than Spain. These maps ought to be enough to get you started in the colonizing game. Make sure to station troops in ToT provinces if you're Catholic, as you don't want to give Spain free colonies. Also note that buying maps will not help much, as you will not gain knowledge of uncolonized land provinces. With a bit of luck and a naval-oriented Land/Naval DP slider, you ought to get at least one random explorer during this phase. Here's where the 17-ship fleet comes in; using the naval reorganize exploit, you can send your explorer-led 17-ship fleet unlimited distances without stopping in port. (Purists would argue that this is cheating, so feel free to refrain from doing this, though not exploiting this loophole will make things a bit more difficult later on.)
Take out the Aztecs ASAP if Spain hasn't done so - the gold is handy, and the CoT in Zacatecas will, through your colonization efforts in America, become one of the richest in the world as the game progresses. Go Narrowminded to maximize Colonists, but not so Narrowminded that you're lagging in the tech race. A setting of 2-4 usually works for me. Colonize as much as you can, but
don't blanket the continent with TP's. Concentrate on building 3-5 colonies at a time, promoting TC's, CJ, and governors when they reach 1000. Target provinces in descending order of tax base, paying no heed to how disjoint the colonies are. The goal here is to maximize income and return on investment, not create a map with pretty borders or color the continent monochromatically.
Secondary goal for this phase is to continue conquering non-capital CoTs as the opportunities present themselves. Take full advantage of the AIs tendency to embargo, as well as the Counter-Reformation, to get CBs when necessary. Generally speaking, no CoT is too far away. If you can take Malacca, Santal, or Shangai, go ahead and do it. Sack Lisbon every now and then to expand your maps if necessary.
Phase III: 1620 - 1700
By now your nation is the unquestioned sole superpower in the world. You may not be the largest nation, but you're certainly the wealthiest, and that's really all that matters. (OK, manpower is important, but given enough money you can easily defeat an AI nation with significantly greater manpower than you.) Time to flex those muscles by systematically force-vassalizing the four most powerful nations in Europe. Typically this ends up being England, Spain, France, and Austria, but your game may yield different results. Also, try to make sure you border all four of them, so you can pick and choose who you will DA to kick off the BB wars. Again, take advantage of embargos to get CBs, but don't be shy about DoWing without CB. Make sure to ally with all four of your vassals.
Secondary goal here is to mop up all the pagans. Not much reason to leave them alone at this point.
Phase IV: 1700 - 1820
Here's where the fun starts. Build up as large an army as you can afford, then DA one or two of your vassals (preferably the one(s) with the longest vassalization times) and sweat profusely as the DoWs roll in.

Since the large, powerful nations are already under your thumb, you'll only be fighting the little guys. Even so, the first few rounds may be challenging. Keep annexing like mad, you'll find yourself assaulting your way through the Mideast and Asia in no time.
Granted, this template won't work very well for Far Eastern nations, and it does rely a bit upon getting a random explorer or two. Also, this strategery would fail miserably in earlier patches, as it does not place enough emphasis on converting provinces. The only times I've really failed with this plan have been while playing nations with rare state cultures.