Regulations are most generally easy to find with a citation.
Finding Regulations without Citation
Ask yourself the following:
Agency Websites. If you know the name of the agency that promulgates rules on your subject matter, look at the agency's website for information, such as enabling statutes, related regulations, reports, press releases and administrative decisions.
Secondary Sources. Use secondary sources (treatises, practice guides, law review articles) to learn more about the law governed by a particular regulation - and to learn more about the regulation itself.
Keyword Searching. Most current regulations are easily findable online. When keyword searching, try to anticipate the language used by the agency in writing the regulation. It may be useful to start with a Wikipedia entry that discusses a particular legal topic to get key search terms.
Use the statute. Annotated statutes often refer to companion regulations. Citators like Shepard's often point to regulations and helpful secondary sources that cite to the enabling statute.
Many online versions of the C.F.R. are updated within 24 hours.
Use the e-CFR for free from the government. Updated within the last three days.
To establish the current validity of an existing regulation, find and read case law (in your jurisdiction) that cites your regulation. Look out for court constitutionality rulings and other holdings affecting the rule's "good law" status.
If you are looking at a regulation in a commercial database like Lexis, Westlaw or Bloomberg Law, then use a citator (like Shepard's or Key Cite) to locate current materials that cite the regulation, whether cases or secondary sources.