The Mac Operating System is a strange beast all on it`s own, therefore this guide (which will forever expand) will cover some questions you may have. Please note that some of the stuff metioned here may already appear elsewhere on the site as a "Tip"

Which MacOS Should I use?
As a rough guide, This is how it works.
68020, Download and use.System 6.
68030, Download and use System 7.x.x for best results but not 7.5.x+
68040, Download and use System 7.5.3 to System 7.6.1.
68060, Download and use System 7.6.1 to System 8.1
*Note that on some processors, Running more than one app at a time on the Mac side could be considered foolhardy.

Back-ups.
Mac OS is by no means a perfect beast. One thing you should really do, in order save your sanity is to back up your system partition. The easiest way, is to open your System Window, check how much space it`s using, (look on the top bar) shut down your Mac, return to your fusion config, create a hardfile of equal size, make sure it`s mounted on boot up, and boot back into your MacOS. Once inside, format Hardfile and copy your system partition over to the hardfile. Exit Emulation, unmount hardfile and as an extra precaution back it up to another hard drive/cd rom for saftey.

Changing Icons
The Default icons supplied with fusion are pig ugly, to change them, download Aaron (See Links Page) This comes with a nice Harddrive icon for Mac use. then: . Click on the drive icon and select from the apple pull down Menus select FILE > Get Info. ( A System window will pop up, click on the Drive Icon, a border around it will appear and once more from the Pull down menu select Edit > Copy. Click on Drive you want to change icon with, repeat the same process, but this time do Edit > Paste. Close window and it`s done.
Search Google for Mac Icons, "Steves-Icon-set" is a good start.

Unarchiving Files
Anything you download for the Mac is always archived in some form or the other, including the archiver! Which results in a bit of a chicken and egg situation, This can be a real pain to find seperately. However, Geofront contains a Goodies Hardfile containing a fully working Stuffit expander utilitity to overcome this. (See Links Page) Beware: Sometimes files downloaded on a PC or Amiga may not download too well. The Mac can be very fussy on how files are downloaded.

Internet Connection - Dial-up
This is really tough! Yes you can connect to The Internet via you Amiga/Mac OS. However, to save yourself problems, Download FreePPP (the MacOS version sucks mightly) and ensure you are running Open Transport (if using System 7.5.3 or later, if not it`s available from the Apple Site, See Links Page) *Note that under fusion 3.1 (May have been fixed under fusion 3.2) your max connection speed will always be 57600. If you are not obtaining this, keep trying different modem drivers

Internet Connection - Broadband/Cable
Vlink Set it up on your Amiga (Miami or AmiTCP) where the broadband or LAN is, set it up in your emulator options, et voila! Your emulated Mac suddenly has an ethernet device
Thanks to Matt Sealey for this information.

Screen Problems
If your Mac Screen isn`t centered, or is too big/small etc, Don`t bother looking for the controls on the MacOS to fix it, they don`t exist! This happens particularly under an Amiga running a gfx card. You will need to exit the Mac and make adjustments, to your Screenmode settings on the Amiga side. Also ensure that all your Amiga 256 Colour/Color Displays are set up correctly, most games will only run on 256 colours/colors