I've been 100% successful over 4 years using the submit and boost method to deal with interdictions. The method is predicated on having a reasonably fast ship. I recommend a boost speed of at least 350m/s, so invest in thrusters and power distributor before anything else if you're doing anything that will get you interdicted, like missions, cargo, mining, passengers, etc. A boost speed less than 300m/s is pushing you into zone of risk.
The method is to travel with 4 pips to engines and 2 to shields, so that you're ready. When you get the interdiction tether, submit and immediately boost in the direction you're pointing. Don't turn to look at who's after you. As soon as you can, boost again, by which time your FSD will be cooled down. Engage it and keep boosting while it charges, then stick your finger up at the NPC.
I have found anecdotally that chaff works OK in normal fights, but has less effect against the NPCs that interdict you. It will always be better to fire off chaff than not.
Heatsinks break target lock when you get some distance from the enemy. Anecdotally, it's 500m, but it might depend on ship temperature as well. Whatever it is, your first boost will get you to a distance greater than that, so, in that case the heatsink is very effective to break target lock, which effectively disables gimballed and turreted weapons and, more importantly, the seeker missiles that the NPCs fire at you when your shields are down. I very rarely use heatsinks because I always have enough speed to get away, but I would definitely use them for any shieldless ship or any that has a boost speed less than 350m/s. The strategy is based on the principle that the damage form weapons drops off as distance increases. That first boost gets you enough distance to reduce the damage and the second boost will get you more or less clear of any damage.
In a small ship, heatsinks and silent running are very effective against real player gankers. Silent running is not so effective against NPCs once they have seen you. They can read your control inputs directly, so they always know where you are and where you're going.