Maths can be a difficult subject to approach if you're not sure of it, there's so many resources out there - so what do you use???
Ideally, something simple to start with, and for us, something which slowly progressed and built on the work already done. Kumon offers maths (and english) tuition to help your child excel.
These Kumon work books are fantastic in our opinion. They build up knowledge, seamlessly moving on to a step up on the next unit. Our eldest likes using these and is working his way through them :) No need for tuition, although they are based around the Kumon philosophy. There's more than just these titles, covering everything from Geometry to fractions.