To avoid blocking you should use accounts that exist for more than 1 year (or at least warmed for 2 weeks) and do not send more than 15 outbound messages a day (you can send 100 and more using multiple accounts) using 1 account. We recommend do similar to this:
1st day: send 8 outbound messages.
2nd day: send 10 outbound messages.
3rd day: send 12 outbound messages.
4th day: send 15 outbound messages.
And then just send 15 messages each day. For about 1-2 days a week it might be a good idea to stop contacting new profiles.