A full-size 1:1 scale is always best, especially when dealing with any raster artwork. When building your document, please make the document page size .25” larger in the height and width. This will account for the .125” bleed required on all sides for accurate trimming. Do not worry about putting in trim marks, color bars, etc. Our prepress department will take care of those items for you and send you an electronic proof to approve prior to printing.
Some files do not require any bleed, such as corrugated signs, real estate signs, Menus, die-cut stickers and shirt designs. For specific bleed settings work with your project coordinator, but in general a 1/4" bleed will put you in good shape.