To get investment, you can do various tasks and activities :
prerequisite would obviously be to build your startup with a deep enriched knowledge and functionality of what all problems your idea solves.
Also startups are evaluated by investors based on 1. your team 2. your value creation to solve a problem.
Go for startup pitching events.
Engage in meetups for startups.
Submit ideas and business models in startup incubation competitions.
As far as the eligibility goes, you just need to make sure that you have a viable business model with a solid idea solving problem statements. Rest all varies from investor to investor.
All the best. feel free to connect for more details