I am not an egoist, so I am leaving this a comment. I don't really want to lay out my own definition of egoism, but, like dot, I have some ideas of where you might look for further ideas.
If you can track it down, the periodical The Sovereign Self might be of interest. It was an Egoist paper that was produced around 2011 - 2013 (I think?). Some writing from it is in the book Egoism that dot mentioned, but outside of that I am unsure if it is available anywhere (a quick perusal of the Anarchist Library didn't find it as a title or by a general search, though I didn't delve into looking for authors or specific articles.
Also excerpted in the book Egoism and worth tracking down is the periodical My Own which is put out by Apio Ludd. Some issues of it are available (or have been) via Little Black Cart. Apio is both biting and sharp and deeply playful in his writing, even when it seems to wander a bit.
Although it is not an explicitly egoist read, it might also be worth checking out Wolfi Landstreicher's work in Willful Disobedience. Wolfi did the recent translation of Stirner's The Unique and Its' Property (aka The Ego and Its' Own) and also did the first full (only full?) english translation of Stirner's Critics. Willful Disobedience was a zine published for about a decade from the 90's to the aughts. If I was asked to classify it by taxonomy of anarchist tendencies, I would say it came from more of an insurrectionary & non-primitivist anti-civ perspective than an egoist one, but I think it is an interesting look at the slow development (or maybe not development, clarification?) of his egoist perspective. The anthologized book Wilful Disobedience is also available at Little Black Cart, and at least parts of the zine are on http://theanarchistlibrary.org.
Hope this is helpful.