I use Saxon math which incorporates daily fact practice. Right now we've covered doubles [4+4], adding 1, adding -, subtracting the same number [6-6], subtracting 1 and subtracting 0. They do a 20 problem, mixed fact sheet each day, and most are able to finish within 3-4 minutes with very few mistakes. We also do flashcards [either whole class or individually] daily, so we get lots of practice.