Go to Control Panel, Select Personalization. I prefer a solid color background. The icons show up better and the eye is less distracted with solid as opposed to a wall paper (some photo on your disc, blown up to fill the entire screen. There are two basic schemes, dark background with white text (aka white on black)(, or light background with dark text (black on white). Win 8.1 allows you to choose the color of the window frame but every thing else (text, selected menu item, etc) is automatically set by Windows. For amusement you can watch Windows switch from white to black text and back again as you alter the background color. And the Microsofties like soft pastel colors with little contrast. Win XP gave much greater control to us users.
Once you have the background and frame colors to your liking, click on "Display". Take the top item, "Change Size of all Items". I made it 125% (the only choice besides 100%). This yields a text size close to my old manual typewriter. The 100% setting makes all the text really small, I can still read it, but the 125% setting is easier to read. I sacrifice some screen space but for me it's a good tradeoff. I'm on a 14 inch laptop, bigger displays might work better at 100%. There are a couple of other settings in "Display" that I haven't tried yet, but going with a solid dark blue background, light blue windowframes and 125% gives a screen that I like.