All Good Things
At this point, you've reached the end of the main Twilight Strand guide. You've gotten your first character to the endgame, played around some with the maps system, have a grasp of the game's core mechanics, and should have some currency to play whatever you want to try out next.
That being said: this guide only touches on the numerous deep and complex interactions that are possible within Path of Exile. You're a prepared beginner now, not an expert.
This guide took many, many hours of work to write, and I'm continuing to improve it today. If you want to support that process, please let me know about any errors you find via email or Reddit.
Alternately, you can support me by donating here. This guide takes quite a bit of energy to keep up to date, so contributions are always appreciated.
Where To Go From Here
If you're enjoying your current build, go ahead and keep playing it - although some of the Guided Builds probably won't survive well into the higher echelons of the endgame. They should be able to handle, say, normal Atziri just fine though.
If not, or if you want to try something new, now is a time to try out a new build. Consider flipping through a Unique item list and finding one to build around (though you may want to ask fellow players whether it's remotely viable to do so).
Consider reviewing the remaining pages in the Mechanics Reference, if you have not already done so, and pick up any missing tools from the Tools & Links page.
Aside from that: I hope this guide has been helpful to you. Presumably you like the game if you got this far, so - happy hunting, and good luck in Wraeclast!