How to build a conviction

To trade bigger sizes, different plays, differents setups,… simply to trade differently you need conviction. The question is, how you build this conviction? Here are few examples:

1) simulator – simulate the older way andncompare it to a new way on bigger sample of data.
2) real trades – after a real trade being done, implement the “other” approach. Did it help the trade? Remember you need more data to decide more accurately.
3) supported opinion – by expert, better trading buddy, coach.
4) visualization – after you have strenghten the conviction little bit, use visualization techniques to make it stronger