How can you really clean out your computer for more disk space

I keep getting the message popping up I have low disk space. I clean out my cookies, temp files, defrag and I seriously don't think it does squat. Is there anything 'I' can do myself to really clear it out and make more room. I know I have a lot of stuff on here I don't need but I don't know what I can actually... show more I keep getting the message popping up I have low disk space. I clean out my cookies, temp files, defrag and I seriously don't think it does squat. Is there anything 'I' can do myself to really clear it out and make more room. I know I have a lot of stuff on here I don't need but I don't know what I can actually get rid of. I also uninstall stuff I don't use but I'm sure there is more I could uninstall it's hard for me to tell if I really need them as to some of them have like 3 things to go with it.

Can anyone suggest anything to me? Or is this something I can't do myself?
Update: Ok what all of you are saying to do I have already done which you would have seen if you read it.

*If there isn't anything more I can do, just say that instead of restating what I have. Thanks.
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