If your phone is a 1ghz, then OC to 1.5 is max you want to go. There are write ups here on XDA, just search. Going too high starts putting too much of a stain on the system. Under voltage can help, but you just can't be applying settings without knowing what they will actually do. There are write ups on XDA about that as well.
Try disabling your animations and other performance robbing settings and run the phone at 1.3 or 1.4. Other than that, you have some reading ahead of you. And make sure you backup up everything, before you apply settings to boot!!
Hit thanks if I helped.
delivered to you piping hot and fresh through quantum physics and pony express