Hello and welcome to my User Tip
This is a method to accommodate those with hard of seeing issues and being able to surf the web easier.
OS X doesn't have the ability to increase the user interface size or text, if you need that instead you can try adjusting the screen resolution in System Preferences or use Windows 7 (and likely Win 8 also) instead as it does have the ability to adjust the UI elements and text.
The settings are in the Start Menu > Control Panel > Apperance (note the custom text adjustment on the left side)
You can install Windows on a Mac using Apple's BootCamp or using a virtual machine software.
For OS X use, install the free Firefox web browser from Mozilla here
Also thake this opporunity to check your installed web browser plug-ins are currently up to date.
Next you need to install the following add-ons for Firefox
Theme Font & Size Changer
NoSquint preferences can be adjusted under Firefox's Tools > Add-On's menu, where you can set a minimal default 160% web page zoom for instance.
Also, if you have the Zoom Out / Zoom In button on the toolbar, any webstire you set a custom zoom will be remembered for the next time you visit.
No need to zoom it again and again each time.
Theme Font & Size Changer can be adjusted under the Tools menu. Experiment with different fonts and sizes to suit your needs.
I find Arial 26 point to be acceptable for my needs and easy to read as it's a rounder wider font. San serifs as well.
To adjust things on the Toolbar area itself
To move items around, add/remove menu items, add more ToolBars, use the View > Toolbars > Customize option and drag items onto the window or onto the ToolBar area to adjust as you like.
Next you visit this page here, and add a Persona, which if you pick a good one will provide better contrast than black on gray which Safari does.
You cand have many installed and chose what you want by visiting the Tools > Addons > Appearance option.
If you want a good choice right away, I suggest trying Fragile Nature, it's a light blue theme with black text, easy on the eyes and doesn't clutter up the menu text with images. It's cheerful without being overbearing, the green leaf is off to the far right so it's just enough fun and not in the way.
See the difference compared with Safari here
The larger your display is, the larger you can go with zooming the text in both the menu and on the web pages and Firefox will remember your window size, so large screen iMac's it will fill the whole display if you wish.