Job Hunt

Hello all I work as a software developer at a seed -> acquired startup. Total work ex is around 1.5years. I am looking for a change now. Till now I have applied to some bigger companies with referrals and some through job portals, only got one call till now after applying at many of them. I want to switch gears in my application now as I want to switch as soon as possible. The next step would be cold emailing decent startups. Could you guys help me with my approach to cold emailing and share some best practices? I don't have much experience doing cold emails because I've gotten previous jobs either through campus/angellist like sites. PS: The number of calls/applications is making me a bit anxious I've tried dropping LinkedIn connect messages to a lot of recruiters and engineering managers but no luck