For a well balanced 10 points, you get a guardsmen not good in h2h that carries a potent weapon and carapace armour.
I usually take 10 or 12 fire warriors per team and normally 2 in 1,500 sized games.
I normally use them in a supporting fire role as you might see with space marine scouts with sniper rifles. I find a piece of cover they can sit in, put them there, and just simply shoot at the closest targets or the targets too far for your army.
Fire warriors are great for supporting fire role. Because if you read this you are either a Tau player yourself, or you are another army trying to steal tactics or figure out how your tau opponent keeps beating you, you would know that there are very few, if any, units venturing too far from your firing line. E.g. battlesuits (with the full intention of moving back in the assault phase) kroot, and stealthsuits. I find that assigning my fire warriors to all kinds of infantry and light vehicles is where they are most effective. Although, note this, only assign units of 12 to light vehicle duties, or you simply won't get enough dice rolls to matter.
The best way to use your kroot is one of 3 ways.
1) Because they're so cheap, you can use them to screen battlesuits so they can't be shot at.
2)This more or less is better than #1 because it combines that purpose into what I am about to describe. Get ahead with the infiltrators rule and wait for an ambush possibility.
3) Shoot like the Tau! The kroot rifle's Ap of 6 is the only thing that stops it from being the same as a bolter, also the bs3 brings you down also, but hey, for 7 points? who's complaining?
Ok, now into detail.
1) screening is a pretty effective tactic, especially for the battlesuits, they are your only medium weapons (S6 to
carriers, although I have seen many a pulse rifle stop a rhino and raider, I have also seen drones take down a leman russ! Anyway, in case you've been hiding under a stone, battlesuits are powerful and pricy. They need to be protected, especially when fighting against space marines (they have access to more lascannons and missile launchers (S8+)(instant death) than any other army. So what out, and if you buy a Shaper, although they are pricy and along with the 6+ upgrade, the leadership bonus should make them last longer when the casualties start to pile up.
2)This is my favourite, kroot look so good when assaulting. They're only matched in looks by the old hormagaunts. Any, don't take a krootox, but I recommend hounds because you'll need that initiative 4 and 2 attacks. I said don't take a krootox because it denies you the infiltrate ability which is so valuable. If kroot are caught in the open for even 1 turn, even lasguns take their toll.
Get in a spot where most line of site is blocked, and any enemy troops can be picked off if your opponent makes a mistake by an inch or so. Remember, this tactic is only good against armies with some troops either with weak armour, or poor assault ability that you know will be coming to you. (with tau, everyone has to come to you) When the enemy rushes up, jump out, don't shoot (you want the extra attack in cc so you can advance and try to wipe them out) and charge into h2h. You have to be sure of the distances because at that range, the kroot will be shot up so badly that they simply will evaporate in a storm of dice. But if you do get in to h2h, at least some lines of site will be blocked, so even if they do get grinded into the ground, their role is fulfilled more or less.
3) Sit and shoot. Here i recommend taking a shaper and the upgrade and as many krootoxen as your points allow. These guys will perform the roll of infantry support. The kroot gun is roughly the equivalent to a missile pod or an autocannon. And the kroot rifle will perform equally well when the enemy close in. Now, if the enemy starts to get close, work your way forward. The krootox is great in an assault, and unless the enemy is S6 (Imperial guard guys with powerfists, carnifex) then your toughness of 5 should save you from any major damage, although assault the guardsmen, the taller than average grass that they are, will fall easy prey, and i do not recommend assaulting a carnifex, that's the plasma rilfes job.
In conclusion, I just want to say that kroot can be so effective if employed properly, i once defeated a ten man marine assault squad! i had a 20 man kroot unit with a shaper and that added up to 62 S4 attacks!! Nothing, not even marines can take that kind of a beating.
On to gun/shield drones.
Because Games Workshop only allows you to get shield drones with pathfinder shas'ui and stealth team leaders, you probably won't have more than 1-4 in your army. So numbers are rare, if that. I always assign them to my shas'o or ethereal, especially the ethereal, he needs to have the MOST survivability (ehem, price of failure, ehem). Shield drones are just something to take hits the armour piercing hits for you. I once had a battle (it was a modified version of the Last Stand mission. CDN/US white dwarf 267) where not until after three turns of space marine shooting, did I take an actual Tau casualty. Before then, only my screening kroot and gun/shield drones had been doing all of the dying. So as you see, they can be effective with the right layout.
Gun drones. (independent)
These guys I only ever take when there is the deep strike rule allowed. the best tactic for them is simple.
A) Deep Strike behind enemy lines and pin an important squad. e.g. a heavy weapons squad.
B) Deep Strike behind a vehicle and blow its brains out with grenades and plasma pulses.
(This does work. I have sent 3 out of 4 Leman russ battle tanks to the great machine god in the sky this way)
BS2 isn't great, in fact, it sucks, but the twin-linked factor makes it better and i usually hit with 3-5 of 8 shots. O, I forgot to say, always take a unit of 8, only in a unit of 8 will they be able to take casualties and still be a thorn in the enemy's side. Once you are reduced to below 4, consider you unit gone. Immediately when a morale check needs to be taken. Leadership 3 (-1 for being below starting strength (
) will not hold up at all.
Find a good spot and stay there. I don't even see why they need a devilfish aside from the forward scout rule they are a waste of points. They only purpose they fulfill is a seeker missile rack. Always take 4, it is better to have more than not enough, but having the right amount is great too, for me, the more guns, the right amount.
I normally just find a good sniping position and let loose. In that same modified last stand mission. My pathfinders were responsible for 2 enemy dreadnaught kills, and 1 rhino and 7 marine kills before they were brutally slaughtered. There points was matched and i was happy. Their pulse carbines aren't too great but use them when you have to relocate, you might even pin the enemy down.
This guy, is a big guy, and a pricy one, it is the most expensive sole transport available (I say sole because some other transports have other roles too, like the land raider). For 80 points. I rarely find It meet its own value, but the firepower it attracts is enough to save its own point value. I normally tool it up to the max. Multi-Tracker, Targeting Array, Decoy Launchers, Seeker Missiles (4), and it all comes to a whopping 140 points! Then, it has to survive to be able to earn its value throughout the game. The burst cannon isn't too great, but with the targeting array, it can be much better. With a targeting array, it will hit more, which means more wounds, which means more kills. I have one devilfish, which i dubbed the 'blessed fish' because in one game it killed more than 10 chaos space marines.
Of course, the above kills were of pure dice roll, but most of those good or bad rolls balance themselves out, and the game is 85% tactics and strategy. The other 15% is your opponent's tactics/strategy and dice rolls.
But your little warriors can be as effective as battlesuits if you wish for them. I want to leave you with this comment from my friend when he fell just out of assault range when one of his squads came up close. "Never, NEVER go into rapid fire range of pulse rifles, NEVER"
His squad was annihilated.