Use a good screen cleaner or cloth for such... as far as the keyboard, run a nearly dry cloth over the keys to clean them but the, at your nearest electronics shop or computer store, but an inexpensive can of compressed air to blow out the crumbs, dead bugs, small children or shih-tzus...
i went into my local diy shop ...well know for being a bunch of sexist old farts, who snigger and smirk if a woman goes in there.
i asked for compressed air...he began to smirk at his shopmates, shook his head and was about to become smug and tell me id been sent on a wild goose chase - you know like tartan paint, bag of fallopian tubes etc ...and i just said oh dont you know what it is? its for cleaning computer components or camera equipment etc...maybe its a bit specialist... never mind, and walked out....he just looked at me dumbfounded...haha
i was amazed at myself that i was that quick and firm haha