Most commonly, I do it all separately, because we save more that way. But, we are also retired military, and can't get military discounts through packages (at least that we've found). So, I always check Get Away Today to see if they have a better offer, but they've never been able to beat piecemealing our own plans.
Really, you need a way to get to the resort (place, train, automobile, and any necessary transportation to and from there, like uber), a place to stay (hotel, motel, camp, RV, VRBO, or AirBnB, etc), and tickets to the parks (Last Minute Travel Club is often the cheapest, apart from military tickets or convention tickets if applicable).
Really, easy peasy overall in comparison to WDW. We're heading to WDW in a few years, and my head is spinning at everything to learn and choose and figure out! DL is so much easier to me!