“Firstly, secondly” vs. “Firstly, lastly” when listing just two points

Normally, if we which to illustrate our points, we can use firstly, secondly, lastly (or last but not least or finally).

There are a few pieces of information we need to notice:
Firstly,
Secondly,
Lastly,

But consider that we have only two points, are we going to use

There are a few pieces of information we need to notice:
Firstly,
Secondly,

or

There are a few pieces of information we need to notice:
Firstly,
Lastly,

It seems like firstly→secondly does not have an ending, and firstly→lastly seems to be too fast to end. Is there a better way to talk about them for when you have just two points to make?

The options open to you are as varied as the venues in which you might use them. You are limited only insofar as your powers of invention limit you. In a slightly humorous (humourous) vein at an informal gathering, you might say to the audience:

The information before us consists of good news and bad news. Do you have a preference as to which should go first? [The audience either shouts out which it prefers or stares at you dumbly, in which case you would give them either the bad- or the good news, as you see fit!] OK, the bad news. . . . Now the good news . . ..

In an august gathering of professors emeritus and board members at the dedication of a new science wing on a university campus, you might say:

It is my inestimable privilege at this truly special occasion to highlight two equally important pieces of information. First, . . .. And second--and perhaps more important-- . . ..

Another possibility in a pedagogical context could be worded as follows:

The two pieces of information we need to notice in particular fall into two broad categories, and the first is information that is clearly irrelevant to our purposes, and the second is information that is clearly relevant. As for the irrelevant information, we need not consider . . .. As for the relevant information, we need to consider . . ..

Here's another suggestion:

Of the six pieces of information before us, only the first and the last require careful attention. The first says, "Blank blank blank blank . . .." The second says, "Blank blank blank blank . . .." As to the first, __________. As for the last, __________.

The decision as to how to format or partition your information is really up to you. Adapt whatever format you choose to your subject matter, your audience, and the occasion. Oh, and drop the "-ly" ending after first, second, third, etc. It isn't necessary, and it does not make you sound more erudite (in my opinion).