Start building a client base by doing small jobs. Personally I went around looking at forums for people who needed bugs to be fixed on their website. Set your price as low as possible to higher the change of you actually securing these jobs, and then perform excellently.
If you perform well enough, you'll find these clients getting back to you with bigger jobs. Two years after doing exactly this for a period of only a month, I am still working for a large percentage of these clients, and their contacts to whom I was recommended.
Getting the engine started is the hard part here. As soon as that's done you simply have to focus on keeping the quality of what you're doing high.
Reddit might work, although I have never tried that. Depending on where you are from, different sites might give you different results. I suggested that being a Dutchman myself, I would build a better relation with Dutch clients, so only went on looking for those.
That "location filter" might have reduced the competition, something which enlarges the change of you getting the job. Finding a job at a place where thousands of others are trying the same might be hard as a starter.
If you perform well enough, you'll find these clients getting back to you with bigger jobs. Two years after doing exactly this for a period of only a month, I am still working for a large percentage of these clients, and their contacts to whom I was recommended.
Getting the engine started is the hard part here. As soon as that's done you simply have to focus on keeping the quality of what you're doing high.