PSK operators tend to hang out at certain frequencies on the bands. Some of the frequencies are dependent on the location of the station, due to local regulations or QRM. Here are the most common:

Almost all of these are the transceiver settings for USB operation, so most PSK signals are within the 3 kHz above these frequencies. (80M operation tends to be both above and below 3580, and there's always W1AW's code practice to avoid at 3581.5) By convention, BPSK is symmetric, you can also operate in LSB mode - just set your transceiver 3 kHz above these frequencies. (If you operate QPSK you'll have to use the "invert" setting in your software.)

Back in the early days of PSK31, the suggested operating frequencies all ended in ".150 kHz". This was at a time when tuning was done using the transceiver. Now that all PSK software is "click and tune", this level of detail is unnecessary. In fact, you only need to set your transceiver "near" the above frequencies, where "near" is defined as within a few hundred Hertz - you'll be able to tune in most of the activity with your software. But don't forget to tune around a bit when the waterfall is very active, as some stations may be operating outside of the "normal" range when there are a lot of stations on the air.

When you are operating USB, your actual transmitted frequency (the actual frequency of your PSK signal) will be equal to the sum of your transceiver setting plus the audio offset displayed in your software. Some people prefer to quote this as a sum, as in "14070 + 1200" for a transceiver set at 14070 kHz and a 1200 Hz offset. Others will state this as the sum itself, 14071.2 kHz. Both of these are exactly the same, as would be someone working the same station with a transceiver set at 14069.5 kHz and an audio offset of 1700 Hz. Note that if you are using LSB, you have to subtract the audio offset from the transceiver frequency. For the exact same operating frequency as above, an LSB station may be set at 14073 with an audio offset of 1800 Hz, which could also be quoted as "14073 -1800".

Many thanks to W3HF for the bulk of this page. The comment about W1AW came from K8IJ.