It's good to see people coming back to film after digital. Rare phenomenon, but a great one.
It's natural that after shooting digi for a while, film is hard because the camera wont enhance your pics and figure out stuff for you. You'll have to get used to it and this might take a while and will probably be disappointing at times. I started phototgraphy and learned with a film slr, so it was sort of easier.
Unless your hands shake a little when you press the shutter or if you have a really bad lens, focus shouldn't be a big problem. Once your hands get steady, there's no shake. Other than that, one little thing you should never forget: focus before you actually close the aperture. It's that silly, but sometimes when I don't have time to think and just go for the quick shot, I forget this and focus sucks.
As to ISO and exposure... It would be easy to explain in a few words, but here's my advice on this: read a book or visit this site:
http://photonotes.org/
When I was starting with film, I got very few and nebulous explanations from some people and finally wasted lots of film before I could really figure it out.
Seriously, it will save you a lot of time and probably some money too if you read a book or something. This way you'll really know what does what and how to control exposure
However, I must add that just reading wont fill the blanks and you'll have to learn 99.9% from practice.
It's normal that your first roll isn't very good.
The switch to film and even more so to manual can be rough because you're fully responsible of the results.
However, once you have it, you'll see they'll be better that when the camera figures it out for you.
Good luck with this
