The first consideration to ponder is where are you going to do the work... In a garage with a lift or in your driveway on the ground.
If you can rent a lift at a DIY garage they/you will need to have a trans jack to put under it. Regardless you'll probably need to remove the exhaust and drive shaft and various shields to get it out. This will be the quickest.
I have in the past done clutch swaps on the ground with the car raised but I wouldn't suggest that. You're much better off disconnecting everything, and lifting out the engine/trans in once piece; replace everything, then lower it back in.
In either case expect every bolt and nut to be seized and require forceful removal, I'd start by ordering all new connective bolts for the exhaust. Perhaps gaskets for where the pipes separate.
Look at that site from the post above, I'm not a specialist on the 318i but it's basically all the same jazz.
Performance one step at a time.