My biggest tip would be to declutter everything so that the rooms looker bigger and possibly brighter then they actually are. Obviously you still need to use things such as kids toys but I would remove all but the essential and store them either in a shed or someone elses house for the duration. You want the floors to be clear - so remove any toys, beanbags, kiddies couches etc.

When we purchased our current house the thing that sold it to us was that all the rooms were pretty empty besides key pieces of furniture so we could see how big they were. It also allowed us to visualise ourselves in the house with our furniture, we werent overly distracted by the vendor's stuff.

I would also recommend dusting blinds (but that is a pet peeve of mine ).

Fresh flowers add a nice effect.

Remove all appliances eg toaster, kettle etc from the kitchen bench to clear that up too.