For pirating Pirates (sic), you'll tend to have better luck avoiding the whole "get a pilot to bail, pull up alongside, then have it blown to smithereens by a police patrol" issue if you avoid race sectors - Core or Border. For me this generally ends up meaning somewhere in "Pirate Alley" (south of
, although given you know Reunion you'll likely know the place!)
You don't get police patrols through there (unless they're drawn through while chasing something), and military patrols are fairly sparse. You DO get a lot of pirates, so once you start to get on their bad side this could become an issue...but then, they'll be shooting at YOU, not at their mate's ship you've just emptied out.
It's possible to cap TSs with a Buster with IREs (although M3s are a good step up to take as soon as you can!). Get a freight scanner - it lets you see what weapons a ship is carrying/has equipped, and you can use it in Pirate sectors with impunity.
Look for a TS that's not with an escort/in a formation (unless you're confident that you can take them out quickly...which, in an IRE-fitted Buster, is likely to be rare). Find a solo one. Check its cargo and weapons - make sure it doesn't have anything too nasty (particularly that would fit in a turret - you're going to be playing with its rear turret, so you don't want that to have anything too meaty in it). If it's got less shielding than you would expect (e.g. 7mJ instead of 25mJ) then so much the better. Unshielded, underequipped, solo TSs are what you're after. Valuable cargo is a bonus.
Get behind the TS, match its speed, and CHECK YOUR SECTOR MAP. You don't want to be surprised by anything hostile or nasty creeping up on you while you're occupied. If you've got missiles, work out which warhead(s) will take out its shields. Hit it with those first. If you're lucky, it might not even turn hostile at this point. If it does, never mind, it was going to happen anyway. If you haven't got missiles, just start hammering it with your IREs. Hopefully they do more damage than the shield regenerates*.
Then just keep hammering (gently) away at the hull. If the hull gets down too low, it might be better for you to comm the ship and try to apologise, rather than blow it up. The 'Pirate' faction does actually have a reputation meter, like the races, but it's not visible. If that gets down too low, you'll start seeing a lot more 'red' pirates than 'blue' pirates - which then makes capping them more tricky.
ApricotSlice's guide is, as ConscriptFive said, still the watchword to go by. DelRay's guide (afraid I don't have a link handy) is still also valid, though deals much more with boarding ops rather than capping.
Hope some of that's useful!
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* This is one problem with attacking an 'undershielded' ship - the smaller shields will regenerate faster, percentage-wise. This only really becomes an issue once you start boarding stuff with marines (e.g. M6s), because you need to keep the shields under a certain percentage value. Not an issue for capping TSs or smaller ships.