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?
You can try Problogger Jobs. You should be able to find lots of writing opportunities. There are lots of other job boards out there for writers specific.
Follow Nicolas Cole on Medium: https://medium.com/@nicolascole77
Read all of his articles and follow his advice on becoming a freelance writer. Quora, Medium, your own blog. You just need to write a bunch in places that you can get feedback and get noticed.
You can also follow Tom Kuegler for some great tips on building an audience: https://medium.com/@tomkuegler