can anyone share what is the effective method that is convenient for me to remove but at the same time makes those who wants to park will think twice of parking?

would appreciate methods that are tried and tested

P.S. I am refering to outside of my gate, either the entrance or the wall beside my entrance

btw, i am not a mean guy. i won't go and vandalize ppl's car. i just don't want them to park there

thanks