ERC20 tokens are open source and can be created fairly quickly using the public source code that can be found here: https://www.ethereum.org/token
You still need to do basic variables and create the rules around your token but in essence the framework is there and you then need to address what you want your token to do, how many you want to issue etc.
What’s great about the ERC20 token is that it is recognised by the community and can be easily integrated onto public exchanges and traded.
It is possible to issue your own unique tokens but this will mean you will need to address many issues such as how the token will be mined, stored, security and more complex problems that come with developing a core token platform.
Tokens ICO Source code
One of the best practice in ICO’s is to publish your source code for your token to allow the community to check the code and make sure that it is acceptable and does not have bugs. This is also a good way to work with the community to ensure that your supporters have transparency and can feel that the project is open and part of the community.
Hire a blockchain developer
The last point here is that if you are not a block chain developer or super geek better find someone to help you fast before doing this on your own. The token is core to the offering and you don’t want to mess up the very thing you are selling at your ICO.