Whatever the weather, twilight can be a great time of the day for photographers as there's a short window where the fading natural light produces a deep blue sky and the artificial lights that will slowly be turning on balance nicely with it. From now and well into the winter months are great times for twilight photography in and around cities as the sun sets sooner so lights will be switching on in buildings at a more reasonable time.
For twilight photography you do need quite a bit of patience as there can be a bit of trial and error involved when trying to capture that perfect moment when the light in the sky and manmade light balance perfectly.
As the twilight window is small you need to know where you need to be in advance so you can set up as the sun sets, if not before, and be prepared to work quickly.
When it comes to packing equipment, you will need a tripod because as you can imagine, exposure times will be on the longer side at this time of day. If you happen to be out without your tripod just look for something stable you can use as a support and switch on your camera's self-timer so there's a delay between you pressing the shutter button and the exposure beginning to avoid shake. It can be tempting to crank up the ISO level to shorten exposure times but quality will generally be better when using lower ISOs, lengthier shutter speeds and a support.
If there's enough light, switch to an aperture of f/8 and work from there to ensure you have good depth-of-field. Generally, you'll be able to leave the shutter speed decisions to the camera but feel free to switch to manual if you prefer to work this way. You will probably have to focus manually as autofocus has a habit of searching in dark conditions.
When it comes to metering, switching to spot metering can help but again, this method isn't set in stone. Your histogram will also come in handy when reviewing your shots and remember to keep shooting images using various exposure lengths to capture as many different results as possible. Keep an eye out for burnt out highlights which are easy to see when previewing the image as well as on the histogram.
If you want to try something a little different, try experimenting with white balance settings or try applying one of the built-in filters available on your Pentax camera. On grey days, for example, you may find the colours need a boost of warmth while cooler tones can make some subjects really 'pop' from the dark background the sky creates. In some situations you may find AWB introduces unwanted colour casts, too, so you'll need to switch to another built-in setting or work manually.