Without wishing to sound like a know-it-all, curses can indeed work - all magic
can work - it's just that more often than not it doesn't, for a variety of very good reasons.
And without wishing to sound like I'm attacking anyone's beliefs (as that is not my intent), rather than magic utilising some external (perhaps divine) agent or force, magic is the manifestation of the force of the individual practitioner's will.
That magic does work for people who
do believe they are calling upon some external force (including occasionally Christian prayer) is, to me, testament to the power of the force of individual will.
All I would say, in the light of the foregoing, is that if one decides they would like to curse someone, then they had better be damned sure they can honestly say they don't give a damn what happens to their intended target.
If you wish to cast a curse, you may be satisfied with them merely bursting out in acne, losing a job or breaking an arm, but - and this should always, always, always be remembered -
they might die.It is for this reason that I always countenance the exhaustion of every possible, worldy action against an individual who has wronged you before the use of ritual should be contemplated.
Even then, rather than curse the individual, ritual magic can be used as a powerful tool to purge the negative impact that person is having upon you, without having to secifically target/harm them.
Even those who do not believe in the power of ritual can, I suspect, sympathise with the use of such a vehicle for psychological self healing.
The question one should ask oneself is whether the person concerned really deserves to have such power over you as to make you hate them so much? I guarantee you, if you ask yourself that whenever you feel like cursing someone, you will probably find you rarely - if ever - cast another curse.