Since you are interested in software companies, what skills do you have that will provide value to them? If you have tech skills, call them directly and ask a decision maker if they are currently doing "your skill", and if they are not, explain to them how adding your skill will be benefit their business. You can do this with any industry by the way. Cold calling is not for everyone, but with enough calls, it will work and your skills doing this will improve.

I found the Stanford Search Primer to be pretty helpful in building an idea/mental image of the space. redacted