The first thing to look out for, is a proper server configuration and proper security for future clients and what is this marketplace you are talking about ? how does it work ? you need to clearly explain what is this website for and what is your roadmap. ?
If you want it to be successful hire an SEO manager, create campaigns like signature or bounty, in short advertise more and the product. If its useful then investors will come surging to you but if it fails you need to rework it.
Crypto marketplaces are usually getting more beneficial as well as popular so most of the investors would turn themselves towards investing into the such platforms.
Marketing would always play an effective role in running these kind of projects from the start so any individuals who are even thinking to launch such marketplace should first try to think about an effective mean of marketing as there is a whole lot of competition in between the markets and you really need a strong marketing team behind any such platform so that most of the peoples might come to know about your marketplace. Also try to cover as much information as possible in the Initial stage itself so that peoples could bookmark your thread and speculate your marketplace until it is entirely been developed.