Depends on the variety of tree. If its a Prunus species, then wound paint may help to prevent silverleaf infection, but otherwise, wound paint is no longer recommended, since research shows that it does not prevent or stop any infection of the wounded area, and in some cases appears to be detrimental to the healing process.
When you prune the tree is much more important, and the method you use - a clean cut, without damaging the 'collar' or main trunk of the tree itself, and cutting just above a node, as you mention, are necessary, but some trees are better cut back when they are dormant, others at other times of year. Knowing the variety is necessary to advise further.
UPDATE: Acer varieties bleed profusely if cut before end of July in the UK because the sap is flowing strongly - you need the sap to be down, not rising, so best time is really late autumn/very early winter to be safe, although given you're in Canada, the sap might be dropping now, not sure. Might be wisest to wait till September.