What is your ICO? I think it all depends on your project, website look and marketability of your product (if there's a product involve).

1. Project - ICO these days are just a copy-paste of one another, people are so tired of these kind of project. Its better offer something that has not been offered before, something different.
2. Website Look - This is the very important part. Your website/landing page must be enticing, neat, and free of errors to give confidence to possible investor.
3. Marketability - Same with no. 1 just make sure your marketing team knows where to target specific consumer for your ICO, targeting all of possible consumer won't help. Concentration is the key.