The No. 1 strategy for earning as much as you can from a CD investment is to diligently shop for the top rates. After that, the next most important thing is to keep the funds invested for the CD's full term, to avoid incurring an early withdrawal penalty that will reduce your earnings. But unexpected things happen in life, and you may find yourself having no choice but to cash in a CD early. Because of that possibility, it's best to pay attention to the early withdrawal penalties of different CDs you're considering before you buy one. Another strategy is not to put all of your CD investment into a single certificate. Instead of opening, say, one $25,000 certificate, you could open five for $5,000 each. That way if you do need to access some cash prematurely, you may only have to break one CD and can keep the other four intact. Additionally, you could open the five CDs at different places at different times, to try to capture rates that may be rising or from institutions that are offering limited-time promotional CDs.