If u really want to share something, you have to let it free so others can improve your work and play with your amazing piece of art.
Don't you want your work shared with the world? Isn't it good when someone likes your work enough to make a derivative work? And if you choose CC-by or CC-by-sa, then all derivates must mention your work and your name.
A good permissive license will prevent any possible theft by making it legal.
Perhaps, but it depends on what you'd intended for it - if you're not too tight on its context and you'd like it to be seen by a load of people then it can sometimes be a good idea.
see posters for this conversation
see all posters
see all conversations