High needs/clingy toddler?

My son wants attention, to be held or nursed almost all the time. He is starting to experiment with being "mean" or breaking rules and tantrums. I'm scared I handle it the wrong way. When he hits I show him gentle and if he continues to hit I stop holding/nursing/ playing and walk away. When he tantrums I tell him "Im sorry your frustrated and I pick him up and take him outside/ never giving into what he want." When he gets into something bad, like climbing or dirt I tell him no because (reason) and if he keeps doing it I yell at him and change the room hes in. I'm scared what Im doing wont work and that he will be bad :( :(

I just want him to grow up to be a healthy intelligent happy man. Is there a way to parent a toddler whom is like this in a way that builds him to be a good person.