There a bunch of threads about this topic in the digital photography area on MRs. May I suggest you start there and read a bit.... it is full of good advice, though often it may seem contradictory. However, different people have different ways of doing things and it may help you to figure out what is best for your needs.
If you have questions as you read, please post those - the digital photo folks are really generous with their time and advice.
Just to get you started....
iPhoto (like Lightroom and Capture One) is a Digital Asset Manager (DAM). Essentially a database. To use it effectively you need to understand that Albums/Events/Smart Albums etc do not contain your photos... they merely contain links to the photos and the database record. Your original images are never altered in a DAM - the application keeps a record of what you have done in your edits (both to the image and to the metadata). This means you can create multiple versions of the same image (BW, cropped, weird colours) without duplicating the image (in theory, iPhoto doesn't do this well) - it is only notations in a database file.
It is actually a good thing you can put a photo into more than one Album...that's the whole point. You can have an Album for Paris, and one for your dog. If your dog is in Paris then you put the photo into each Album. Now you don't need to remember where you filed the photo...it is in both places... and it doesn't take any more space. Also, if you add notes to the photo they will appear in both Albums.
I don't use iPhoto much anymore, but I barely touched Events at all. I did all my organizing with Albums/Smart Albums/Folders. If I was in an Event it was simply because I wanted to find a photo that I remembered taking about the same the same time as a photo I was looking at in an Album. Do your work with Albums and Keywords, and you won't need to head into Events often.
Good Luck.
