When you design presentations, make films or take pictures, often the file size ends up pretty large. But when putting things on the web, because they will be viewed on screen, high resolution often isn’t necessary and makes for slow loading. (You can always upload a full resolution file if you need to and provide a link to it, telling people its size. )
So here are some tips for reducing file sizes.
Presentations and Pdfs
Presentations can usually be exported as pdfs. (They work best viewed in Adobe Reader rathe than directly in the browser as you can click through page by page. Recommend to your readers they open them in Adobe.)
Pdfs need optimising in Acrobat professional.
[Open the pdf you want to optimise. Go to Advanced/Pdf Optimiser...]
Images
You need a good image programme to change the resolution of photos so they are not unnecessarily big for the web. If you resize the image in a layout programme or a programme like WordPress, the final image quality may not be so good. Not so good but free for the Mac is Pixer, a tiny app that allows you to choose a picure resolution you want.
[Fireworks is good for this. Open the file you want to reduce. Go to Modify/Canvas/Imagesize and choose the size you want. Check resample image]