Colonize the coast before the inland to block out other colonizers - no matter who you are, the other western Europeans are bound to show up in the new world before long, especially Portugal.
Make sure that you have at least one big ship per colony. Having any less will reduce your income from your colonies.
The Colonial Conquest CB is good for when a nearby opponent's colony is at about 800-900. A colony becomes a regular province when its population reaches 1,000, so taking a colony at 900 population means you pretty much get a free province from the war - I think there may be 1-2 infamy for each taken, I'm not sure.
Make sure you have a garrison in each colony until they become provinces. One or two units will do. If you're bordering another European's colony, it'll be better if you had more men in that colony. Natives can rise and burn your colony to the ground in a day, and you can't transport troops there in a day.
Colonists can be in short supply and expensive. The colonial ventures national idea is good for the extra colonists, and the Viceroys national idea is good for the extra income, but you should wait until you have a lot of colonial land until you get Viceroys. Make sure your economy is stable before starting to colonize. If you have to mint (add money directly to treasury) most of your money, you will be behind in techs. It might not be worth it to pay for colonial maintenance too.
Sometimes, it's necessary to send five colonists to five different colonies in order to take the high-value provinces for yourself - such as the Caribbean - but other times it would probably be best to send all of your colonists to one or two colonies to keep colonial maintenance down and upgrade them to provinces faster.
Remember, your colonies are supplements to your homeland, not the other way around. Protecting your mainland European possessions is priority.
