How do I improve my credit score?

Hi everyone, I have been going through my credit scores lately and feel as if it is time to get someone working on it. I really don’t have any particular reasons so as to have low scores but I need someone to work on them to make them better in case of a loan (that I expect to take in a few months) I need. So, can you please suggest me some good agencies that could help me out.

Thanks in advance!