Here are the list to follow to get an ingress invites
There are Google employee that are giving free ingress invites when you follow them in their Google+ account.
First step is to add one or all 4 of these people into your circles on Google+:
#Ingress and/or #IngressInvite..
Or you can simply click this --------------->> DOWNLOAD Free Ingress CODEWhile waiting for your Ingress Invite, Go check the must to know in playing Ingress. Visit here : Ingress Level up Guide
Lastly , Dont forget to share this to all your friends.