Any touch they can attribute to you beats silence. If you don't know what to say, say anything.
The send mantra from week 6 of my coaching program: "If you know what to say, say something. If you don't know what to say, say anything. The worst thing you can do is say nothing at all." The one condition is that they know it came from you. Being the 86th like on a post doesn't count, because your gesture disappears into the crowd. Remember Yo? In 2014 an app whose only feature was sending the word "Yo" raised a million dollars. Bless capitalism. It also proved the point at the smallest possible scale: getting one told you somebody thought of you.
A coaching client spent hours and a couple hundred dollars choosing the perfect bottle of wine for a referral partner. A week later he fired off a quick check-in text to someone else. Which relationship flourished? It doesn't matter. Both did the same job: they showed he cared. One took hours and could backfire ("er, thanks, but I don't drink anymore"). The other took seconds. My Contactually cofounder Tony Cappaert had the same unlock. What held him back was not knowing what to say, until he started defaulting to a simple "I was just thinking about you today."