Here are some useful resources that were used for creating these free powerpoint templates.
Firstly, I used lots of different fonts (many of which are standard fonts that everyone has):
Standard Fonts:
• Arial
• Arial Black
• Georgia
• Impact
• Palatino
• Times New Roman
• Tahoma
Other free fonts used:
• Aller
• Caviar Dreams
• Century Gothic
• Clear Sans
• Coolvetica
• Copperplate
Your downloaded powerpoint template will look better if you have these fonts installed on your computer (or just a particular font that the template uses).
Most of the images used in ppt templates are from these websites:
• Pixabay
• Freeimages (earlier known as sxc.hu)
In latest designs free icons from SmashingMagazine were used. Some other great resources for beautiful and free icons that you could import into your powerpoint template are IconArchive and IconFinder.
And finally, I suggest to use a consistent color theme in any powerpoint presentation that you create. I used this great free color theme generator. Color Schemes Generator also looks very promising.