For me it's always a combination of the following: (1) not feeling ready (2) not feeling like I have spent enough time building an audience/followers around it (3) worried launch will not go as expected. What do you find the hardest?
Very quick and easy to use - it's a web app so no installation needed and it doesn't require registration. Simply add a hex code of the colour you want to match, choose a 'harmony' (i.e. the type of match you would like) and it generates a colour scheme.