Methinks that a good way for GOB to raise revenues is by applying a low-import duty, e.g. 2 to 5%, on those articles that come in absolutely free of import duty. Cooking oil, stoves, refrigerators, disposable diapers etc. This level of tax would not hurt the consumers too much and would not encourage evasion.
On the other hand, charges for toilet bowls and accessories should be lowered so that usage of pit latrines is discouraged.