We've been contemplating on hiring a baby sitter. But the thing is, we don't know anyone. Is it safe to go to agencies and hire someone who you don't know?

I will think it's safer to get recommendations from parent group on Facebook or forums. There is this Facebook group which parents recommend baby sitter, nannies and maid. You can try asking for a recommendation around your area. https://www.facebook.com/groups/790785207700722/