How do you check and adjust the resolution and color mode of your Photoshop files for printing?

Context matters. The ppi you need depends on the final viewing distance. There is a point at which individual pixels in an image are too small for the human eye to distinguish. Call it "the retina value." But this depends on how far the viewer will be from the print. At normal reading distance, it's about 230 ppi. A 3600 x 2400 pixel printed at 12 inches x 8 inches is 300 ppi. That's past our retina value, so it looks fine. Now make it 20 ft wide: billboard size. It will be about 15 ppi, but will look just as good because from 100 feet away it's past the retina threshold. You need to know the viewing distance, in other words, before you can determine what pixel resolution you will need in the final output.

After you've linked or embedded an image into your InDesign or illustrator files and made any last-minute resizing, open up your Links palette (the one with the chain icon). There will be a list of properties. Assuming your document is laid out in actual size, the most important number to look at is "Effective PPI". If its below the target (usually 300ppi for hi-rez printing or 150ppi for large-format banners), then you need to rez-up the image in Photoshop. But a lot of times, simply resizing it in Photoshop may result in a pixellated image. I recommend using a third-party app (like Topaz Photo AI or On1 Resize) that uses AI or proprietary algorithms to intelligently fill in the missing pixels.

Also worth highlighting difference between DPI and PPI. Although used interchangably they are in fact different. DPI referring to Dot Per Inch in relation to printed media, Pixels Per Inch for screen resolution. So everything you stated is correct but if producing for a large billboard is this print or screen? If the design can do away with raster then vector removes the need for DPI/PPI consideration as its fully scalable.

Navigating the shift from RGB to CMYK is crucial for print accuracy—a lesson I've learned over years in desktop publishing. Converting early in your process avoids surprises. Remember, what you see on screen won't always translate perfectly to paper. Use 'Proof Colors' to preview the outcome. This step is key for client satisfaction and professional results. Dive into these settings before finalizing designs to save time and ensure your vision is realized in print. It's a simple but essential practice for all designers.

In some cases (for example, for digital presses or large format inkjet printers), you may be asked to keep your images in RGB, allowing the imaging device to do the conversion. This allows the conversion to be optimized for that particular output.

If you have a good relationship with your printer's pre-press department, you might want to ask for a copy of the ICC profile of their color rasterizing system and apply it to your document when generating print-ready PDFs. I maintain a file of ICC profiles for all the different presses I work with.

Pullup tradeshow banners are a perfect example of unsymmetrical bleeds. Some banner hardware will require a 1" bleed on the top, 0.5" bleeds on the sides and a full 6" on the bottom. The top bleed is to give allowance for the vinyl to tuck into the top retaining bar of the pull-up, and the bottom 6" gets rolled into the spring roller mechanism of the pull-up. Different manufacturers will have different specs so be sure to get the specs directly from the manufacturer or printer you're dealing with.