This big dummy crushed a carbon seatpost by not using a torque wrench. And I certainly know better. I bought a small one that goes down to 5 nm from Harbor Freight. I already have a torx and allen bit set so that didn't cost extra.

I highly recommend getting some Tacx Carbon Prep (AKA Tacx Dynamic Carbon Bicycle Assembly Compound) available at LBSs or Amazon. It prevents the carbon parts from sticking and also keeps things like seatposts from slipping.