cl_updaterate 67 and cl_cmdrate 67 should be used on ALL connections. Our servers are 66tic, so 67 should be used on all clients connecting to them.
Interp settings will differ depending on your geographic location. For North American connections, a lerp setting of 33ms on our servers is ideal. For European connection, the default 100ms is usually best. For best results, don't go below 30ms, or much above 100ms. Note that if your lerp shows up as yellow you will probably have packet loss, and if it is orange it is definitely causing packet loss.
Rate will differ depending upon your connection's bandwidth. If you have an expensive connection that supplies plenty of bandwidth (10mbps down or more), the ideal value is 50000 for our servers. For slower connections with less bandwidth, I recommend 25000.
-Blue