well if you want to master every skill and intend on using trainers you'll want to train as high as you can ( look for master trainers who can train you to lvl 90 ) though this will cost a lot of gold so look for followers who can train you ( since you can take it back ). but you still need a fair amount of gold for this still, and they'll only go to lvl 90 so maybe the best way ( if you dont mind cheating ) is the ohgma infinium glitch
a quick google search will tell you. its also googd to note you can only get to lvl 81 and a half if you master every skill meaning 81 skill perks, so chose wisely on which perks you get.
hope this helps