Utilizing social media (Twitter is popular amongst game developers these days) is a pretty good way to keep people updated about your game. Making a few posts every couple of months is enough to prevent people from forgetting that you exist, but not so much they become annoyed and unfollow you. The content of the posts doesn't have to be particularly much, either - a short gif showcasing a few interesting things that you have added since the last post seems to be the standard. Making such a gif won't take you longer than ten minutes, so it isn't going to eat up as much time as some other forms of promotion, such as creating a YouTube video.
That's certainly good advice :) I'm more wondering where the people who've seen the devlog and then want to play the game will be on release day, and how they'll know when the game comes out.
People will be notified if they follow the developer but I find the number of people who do this to be quite low. I'll use Newgrounds as an example here because I can make a direct comparison- more people have added our game to their favourites than have followed us. Far more people have given our games a good rating than have followed us.
Social media's a good point too, although the number of people who follow us there from the games is even lower. Also, the number of people who visit our games from Twitter- according to itchio analytics- is negligible. Admittedly, this could well be because I suck at social media XD