How to be properly cited with a two-word last name
Make it easy for people to cite you correctly.

People are lazy. When I cite a paper, I usually copy-paste the citation from some website. This can be the publisher's website, the author's website, or some index like Google Scholar or DBLP (for computer science). I suspect most people do this too. So you should make sure the correct citation appears in these places.

Make sure that the publisher of your papers has the correct citation on their website. Put the correct citation on your website (e.g. create an "export citation" link). Create a google scholar profile and make sure it has the correct information. In some places it may be appropriate to even include the suggested citation in your paper itself. These actions won't ensure 100% correct citation of your name, but they will make a difference.

Another note: You get to choose what name to put on your paper. It doesn't have to be your legal name. (For instance, someone who changes their legal name upon marriage may choose to keep publishing under their maiden name.) So you do have the option to choosing a professional name that avoids these issue -- e.g., by hyphenating. Just be consistent.