Firestats what IPsto exclude?

I am very new to wordpress self host. I use the firestats plugin and I see strange visits. Something that doesn’t look like a user that comes directly in my blog (no referrer) and does 4 or 5 hits (usually clicks 4 or 5 posts). When I post a link in facebook or twitter for others to see it, I know they are not visitors from these networks because it doesn’t show a referrer) . The results, perhaps the number of the hits is fake because it includes this fake traffic. And maybe this is the reason my traffic is 3 times higher than the wordpress.com where I was before…
Based on your experience, what IPs should I exclude? How can I know which is user and which is a machine?

When I track them down it shows isp like “Amazon”, or other companies…