While axis-foil doesn't comment on any ill-effects of using Brake Cleaner on his SR9, please don't use brake cleaner on your SR9. Not all brake cleaners are safe for polymer frames and other plastics. While brake cleaner can melt certain 'solids', it won't turn your SR9 frame into a puddle of goo, it could cause discoloration. Better safe, than sorry IMHO. The SR9 only takes me a couple minutes to clean via field strip, Ruger did a good job of keeping it simple.
They make great firearm cleaners for good reason. They work pretty well. I use RemOil, spray and wipes. They aren't very pricey either. Hoppes is good stuff as well.
I didn't clean my SR9 for the first 1000 rounds, zero issues. However, I'm not the rule, most folks field strip and clean their guns after getting home following purchasing or before hitting the range. Most of what you need to do is simply field strip and remove most of the gunk that Ruger packs into the slide. Lightly oil the contact points, mainly give the internals a quick spritz with a spray-type oil. Use the wipes to handle gunk/dirt removal from open surfaces. An old toothbrush works well for nooks and crannies.
Occaisionally, it's a good idea to do a full detail strip (see my How-To's below in signature) and get it all clean.