I have some combos that are not really combos to add.
sh fair + sh fair + sh nair/BBB...
dthrow + sh fair (kinda hard to pull off ime)
dashA + BBB...
Linking two sh fairs at lower percentages has been pretty easy to pull off for me and reliable at that, it might be because of the people I play with. When I'm out of the stage after two fairs, I link a nair or up+b, if not, Mach Tornado time.
I don't use dthrow and sh fair much. As it has been said, dthrow and usmash is usually a better alternative, easier to pull off too.
Dash attack + B has been a very reliable way to rack up some damage. Some characters can DI out of this and I've been punished by dairs when the last strike of the Macchie did not hit, but that happens kinda rarely.