When you are using Adobe Photoshop just start by making your canvas size 3 times bigger (or more) in means of width and height than what its suppose to be and change the resolution to 96 pixels/inch (or more), the default is 72 pixels/inch. When you do implement and make your graphics, make it occupy most of the canvas (its gonna be big) and when you're done just copy merge the whole image and paste it to a new window and just simply re-size the image to the normal size you wanted it to be. Also, if you ever use any effects like any type of bevels, drop shadow, etc... try to implement them properly and not overly exaggerated.
Best regards,