Photoshop, 300dpi, CMYK colour profile with transparent background. Set the page to the size of the art you want to create, stick guide lines on top, middle, left & right sides, then expand the canvas size 5mm on each side, that give you your bleed/overlap.
That makes sure when it's printed the art doesn't come up 1mm short or anything.
Set different layers for each part of the design, one for background, then borders, shapes, text etc. Makes it very easy to make minor positioning and colour adjustments later on.
When adding any layer effects like stroke and stuff to text I usually duplicate the layer and hide the original as a fall back if I want to change stuff later on.