Colon use when introducing a list split across sentences

Solution 1:

At the risk of appearing old-fashioned, it is certainly acceptable to use a colon to introduce a list split across sentences. Just be sure to start the first sentence with a capital letter:

We required three ingredients: Firstly, eggs, to provide a nice eggy flavour. Secondly, milk, for all its milky goodness. Finally, we required flour, to bind it all together.

In modern writing, first and second are preferred. The full-stops (or periods) would also give way to semi-colons:

We required three ingredients: first, eggs, to provide a nice eggy flavour; second, milk, for all its milky goodness; finally, we required flour[,] to bind it all together.

For succinctness, first, second and finally, we required are best removed, as they make the whole sentence rather wordy. Thus:

We required three ingredients: eggs, to provide a nice eggy flavour; milk, for all its milky goodness; and flour, to bind it all together.

You may notice I played around with the commas. That could also be considered a matter of style, but I tend to be fastidious with regard to comma punctuation.

Solution 2:

I will do a full answer here for legibility. Firstly, there is nothing wrong with the sentence you have supplied. However, I agree with Eldros and RegDwight in that you could use a semi-colon.

Having said that, I would modify the sentence when I did use semi-colons, thus:

We required three ingredients: eggs, to provide a nice eggy flavour; milk, for all its milky goodness; flour, to bind it all together.

The semi-colons 'replace' the qualifying 'Firstly' etc, resulting in a punchier, more succinct sentence.