Now is not the time to be socially restrained. I’m not saying you should suck people’s blood, but your freelance lifeblood IS the people you know. Without contacts, you are one thirsty writer.
Go through all the projects you’ve worked on. Which clients did you love to work with? Who is likely to be working now? What did you do for them that made a difference to their work, or made their day easier?
Who was that interesting woman you chatted to at that conference and were going to stay in touch with?
Put a star next to the people you most want to work with and are probably working right now. Email them, individually. Yup. No bland template emails. Write to them like you know them. Remind them of the last thing you did together and how much fun it was. It’s a kind of love letter so make it sound like you mean it.
This takes time so do a handful each day.
Don’t fret when they don’t reply. Some will be too busy. Some are terrible at email. I reckon it takes on average six months from sending a marketing email to someone asking me to work with them.