You might have to readjust depending on the server you connect to. For connections of lower quality you will need different settings than for a low ping stable connection. When connected, you should have the diagnostic tools turned on. Those tools are the latency display and netgraph. The ping is shown in milliseconds and is a smoothed value averaged over a few last seconds.
Lesser value is better.
All below 100 will give you excelent experience, but is usually not possible with a plain modem connection. Modem users should expect between 200-500 and it can all work very smooth if there are not too many dropped packets and your framerate is smooth otherwise. It is displayed as a vertical graph of horizontal lines scrolling up in the loer right part of screen, just above the latency. Netgraph shows how your ping varies with time, whether your connection is dropping packets and if you have any other instabilities. Length of the lines shows its latency - full row equals 1000ms, so one half equals 500ms etc.