Talk to an experienced collector from a nearby BCCA Chapter to learn more. I'm new to beer can collecting. It's your collection. Save them whatever way you want. The lion's share of collectors save empty cans, preferably opened from the bottom.
Some people collect full ones but full cans, especially older cans, can be hard to find.
And steel cans with seams can eventually rust or leak. The newsgroup alt.collecting.breweriana is a discussion area and marketplace dedicated to collectors of beer cans and breweriana.