1.Regulatory Standards-Ex health related website is to be tested using BVA

2.Customer Requirements-some customers require white box testing

3.Level of Risk-more risk use formal testing.

4.Types of Risk-if risk is high use exploratory testing

5.Types of System-lots of calculations use BVA

6.Test objectives

7.Knowledge of testers-If testers can read source code can also try white box otherwise black box

8.Time and budget-If both time and budget are less simply go for exploratory testing.