What kind of writing are you trying to do? Probably the best tactic in general is to find publications and websites that are putting out the kind of work you want to do and try to establish contacts with people who work there via LinkedIn or similar.
If you’re interested in copywriting don’t forget to also check out advertising and marketing firms in your area.
I have been trying to get a full-time writing job but only managed to get a freelance one-time gig. Please any suggestions?