In the attempt to overcome the negative effects of the noise on quantum channels and to provide secure communica- tions, some quantum secure direct communication protocols and deterministic secure quantum communication protocols making use of decoherence-free subspaces and subsystems have been proposed in the literature. However, recent results regarding the use of decoherence-free subspaces and subsystems show that they can be used to convey classical information through quantum channels with unconditional security. In this work, we use these results to propose enhancements into four already existing protocols. As a result, in all cases considered, (i) the encoding was simplified, requiring less gates to be implemented; (ii) the number of qubit and bit exchange was reduced, reaching a four times reduction in one of the cases; (iii) no eavesdropping check nor redundancy are further required; and (iv) the rate of information transmission was increased in all protocols. Such enhancements favor the adoption of such modified protocols in practical scenarios.