Large existing pdf to smaller file pdf for emailing

[DaveG]

Hi,
Thanks for a great product. I have spent a couple of hours trying to make a 1MB pdf file smaller in file size - to make it suitable for emailing.
All the attempts ended up with either background colours changing, pictures changing or no change and regretably no file size change.

Those that ended with pics and background changes were a bunch smaller in file size - just horrid to look at.

Please can you give me some advice on settings.

Thanks
Dave