CCleaner is good. Especially for some simple registry cleanups.
You can also just type msconfig.exe into the search or run it from a run command, go to the start tab and turn off things you do not need in memory. If you don't know if you should turn it off (not start at startup) then google it or ask. Do not turn off something you are not familiar with. It may me important.
I turn off the startup of Itunes, Apple and Adobe. There are others but yo may not have them. Most programs, which you have installed, will not need to startup at startup. Some might though. There is no definitive, as each program has it's own level of necessity to you or itself.