Cramer said he would avoid Multi-Fineline Electronix ( MFLX) because it's too levered to the fate of Motorola. A listener wanted advice on how to start picking stocks on his own so that he can narrow the field without depending on Cramer. Cramer told him to begin by "buying what you know" because that will provide an inside edge. Look at the potholes on the roads, he said. They all need filling and we have a bull market in the materials needed for paving, he said. In that space, he likes Vulcan Materials ( VMC), Martin Marietta Materials ( MLM) and Rinker Group ( RIN). Cramer said that during a trip to the mall, he noticed that Limited ( LTD) stores were looking better than he has seen them in a while, and that he liked the fresh look at TJX's ( TJX) TJ Maxx stores. He would look into these stocks. And he said that he bought Commerce Bancorp ( CBH) for ActionAlerts PLUS because he did his banking there and liked the service he got. He told a caller that he believes Sony ( SNE) is an "undermanaged company." It's getting beaten out by Microsoft's Xbox 360 and by Apple's ( AAPL) iPod. He said the stock isn't really that strong, but that the hot Japanese market has lifted all boats, including Sony. The real investment opportunities are in Mexico, with the Mexican companies outperforming their American equivalents. That's why Cramer likes Coca-Cola Femsa ( KOF), the Mexican bottling company that he says is beating out Coca-Cola ( KO). He likes America Movil ( AMX) for a wireless play, Cemex ( CX) for a building company and Homex ( HXM) as a play on middle-class home buyers in Mexico.