You are encouraged to use a mixture of differential thrust and turning the nosewheel. Differential breaking can heat up the breaks during taxi, and prior to takeoff, makes them less responsive and effective, i.e - requiring more distance should you abort takeoff.
Say you wanted to do a moderatley steep right turn in the seneca, you would approach at a fairly slow speed (walking pace), then coming into the turn you would point the nosewheel in the direction of the turn, reduce thrust on the right engine and increase slightly on the left. Just before lining up, bring the right engine upto the left engine to equalise the power, centre the nosewheel and then bring both throttles down together to maintain speed.
Hope this helps.
obk