To connive is to plan or plot to do something illegal or wrong. Conniving is considered dishonest and cowardly.
If someone accuses you of conniving, that's definitely not a compliment. Conniving usually occurs in secret, and people who connive are up to no good. Criminals planning a bank robbery are conniving. Crooked politicians looking for a bribe are conniving. Villains connive, and conniving is associated with conspiracies and dishonesty. The opposite of conniving is being honest and straightforward.