In the Netherlands, where I live, I don't need to "register" myself to vote. Everybody who is 18 years or older will receive an invitation card summoning you to vote and the address of the voting location closets to your residence. These invitations are given by name. When you want to vote you just have to take this invitation card with valid ID (your driving license also counts as such) and they will check you in on their list and give you the bill on which you can make your vote clear.
All people of 18 years or older are therefore automatically registered, with the exception of people who do not have the Dutch nationality or who are placed under a curator (as that will make all legal bills you sign invalid, and that includes the voting bill. Technically you are back to the status of a child).
Please note, since the 1970s (I think) voting is not an obligation, so receiving an invitation to vote does not give any obligations. If you don't want to vote and to toss the invitation card in the trashcan, you are allowed to do so.This I only do with the water management elections as that is something I don't know anything about and thus I do not deem myself qualified to vote for that. All other elections I do vote for. I also must note that back in the time that you were obligated to vote (you could get fined if you didn't) you still could put an blank voting bill in the box if you definitely did not want to vote. Some people just checked multiple boxes to make sure the vote would be rejected, but as they cannot see who did it, no consequences....