Your first network is co-workers, so being hired at a big or venture backed company with well connected co-workers is a good start. If you get a job doing consu

Your first network is co-workers, so being hired at a big or venture backed company with well connected co-workers is a good start. If you get a job doing consulting at a consulting company, you'll meet new companies all the time in a risk free way. Your second network is physical events - meet-ups, conferences. Note, these should be technical for your field of expertise, not like a business networking meet-up, which suck. Third is your online presence - the open source communities you submit to, twitter connections you've replied intelligently to, etc.