The most important factor is to have a well-defined vision and goals for your project and also be active to your project, there are many communities out there including this Forum , that will help you a lot .
1) The concept or the usefulness of the project and which will be beneficial to the end users.
2) Vision of the management team or the founder plays a vital role in defining the success of an organization.
3) Good and strong team. This can make the shaky project also stable or even stable project can become shaky due to this factor.
4) Making a business plan on paper is different and executing it successfully is different. So execution is the key which drives the product/coin etc.
5) End user review and feedback is the must to complete the cycle and keep enhancing the shortcomings or areas of improvement as suggest by the end user.