"If you win the kids, you win the parents" is a great motto for youth ministry. Parents seem to get pretty excited when they can send their kids to a safe place where they will get to know God. This website showcases VBS programs that come with all you need to know to build a very good program with Adventist principles. Advertisements should be put on social media, into the paper, in front of the school, and provided to all the area churches.
One thing to keep in mind is the timing of VBS. Many other churches also offer VBS throughout the summer, so find out when others are hosting their own event in order to avoid double-scheduling. This will maximize the potential for a larger amount of the community to be involved.