I think the word tactics isn't quite appropriate here. Maybe you should think of a word that describes what was done in a more positive light.
Mahatma(we prefer to use the title he was given with his name) Gandhi had a few objectives in mind to accomplish the goal of gaining freedom from the British. The primary one I think was to unite. The British tactics( it fits in here better) which they primarily used to establish rule over India was a policy of divide and rule. Make the smaller kings fight among themselves, create a divide between castes, religions, etc. In essence, to ensure that no substantially large force was present to oppose them.
It was essential to get rid of this divide and make everyone stand up united against the British. The non-violent way of protest that Mahatma Gandhi adopted, always making his actions speak louder than his words, appealed to everyone, who saw a true leader in him.
I often think that if the freedom movement had been a united effort accompanied by force India could have gained independence faster, but the argument against this has been that violence would have justified violence from the side of the British too and they were better equipped when it came to using force.