It's best that you know now instead of in 3 months - those things are
1) Worth doing because they are one avenue you can find a job
2) Almost entirely useless
1) and 2) are not mutually exclusive. Based upon my own experience and people I know - and more importantly things I've read online about how well these work - although they are worth doing because it's better than nothing the chances are slim you'll actually find a job through one of these things.
Networking is always the best way although I hate to say that because any time anybody told me to network I was like "wtf do you mean?", but seriously those online things just really are not very effective. Do them in your downtime when you're not doing more productive things to find a job.