I use a Chaplain HQ with jumppack.  In high points games I give him terminator honors, and a plasma pistol.  I use him with a maxed out Assault squad with 1 fist, 1 ppistol, meltabombs, and 2 shields.  Very nice fast assaulty squad!
For troops I use 9 ini's and 1 neo in a rhino or 10 ini's and 5 neo's in a crusader all with 1 fist, and a flamer or meltagun.  Rhinos have extra armor, dozer blades, smoke and searchlights.  In high point games (over 2000) I use a Marshall with termie honors, mc lightning claws with a command squad of 1 ini w/fist, 1 ini w/flamer, standard bearer w/fist, +6 ini's with ccw and bps in a rhino. 
For fire support and fast attack I use a Pred. Ann. with lascanon sponsons, PMSB, and searchlight, a whirlwind, attack bikes with mmeltas, and speeders w/mmeltas. I also use 7 man squads with 5 ini's & 2 neo's with lascanon and pgun as dismounted fire support.  I am undefeated in tournaments even playing the shooty Tau and Eldar.  I usually take the vow of hit on 3+/must assault, or initial free move against psychers.  I put the EC in a rhino with 9 ini's equipped as above. 
  Against shooty armies I charge using vehicles (crusader, speeders) and smoke as cover for the rhinos and assault squad in a line ahead formation.  If cover is available I use that as much as possible to save my smoke for as long as I can.  I also use speeders to give my transports hull down cover.
  Against assaulty armies (BA, Orcs, Wolfs, Chaos, etc.)  I usually take a defensive stance with my 15 man squad(s) deployed out front to take the initial enemy charge while shooting them up as they advance.  I target the transports first, then the fast moving assaulty units, then the HQ's.  I hold my rhino squads loaded for counter charging with my assault squad and HQ's when the enemy hits my front line.  I have never lost against Orcs or BA either.  I usually try to assault BA first when they get close so they lose their +1 I and S advantages.
  Keep your mission objectives in mind constantly!  Don't get so wrapped up in killing the enemy that you forget the victory conditions.

The tactics really depend on the scenario being played and the victory conditions.  I'll divide it into two basic scenario types: offensive and defensive.

BT on the offense.
I usually take the troops and support vehicles listed before with fewer foot squads.  Like 3 rhino squads, 1 crusader w/15 man squad, and two foot squads (size depending on the point level we are playing. 

The main advantage of BT is the flexibility of our troop squads.  We can have up to 10 marines (initiates) and 5 neophytes (scouts with WS3, BS3, and Ld7).
We can have one heavy weapon including Plasma canons and one assault weapon (mgun, pgun or flamer).  No vet sergeants are allowed.   

In high point games over 2000 I usually take an assault terminator squad with 7 termies ( 2 with TH and shields).   I take 2-3 landspeeders with mmeltas and a full assault squad as listed before. 

The HQ is the Chaplain with jumppack.  In high point games I add the Marshall and command squad.  I use the Predator Ann. w/lascanon sponsons, searchlight and PMSB, and Whirlwind as heavy support.  I equip the foot squads with lascanons and pguns. 

I launch my assault using as much cover as possible and move 12" a turn down one flank.  I use the speeders as mobile cover to give my transports hull down benefits as I advance.   I save my smoke until I no longer have speeders or cover left in front.  My transports travel in line ahead formation with the speeder(s) first followed by the Crusader,then the rhinos and finally the assault squad.  I give my transports dozer blades and I move right through woods using the hull down benefits they provide.  The predator I usually place in woods in a good firing position to provide fire support for the advancing transports.  The whirlwind is usually placed behind woods in a central location to bombard troops and light vehicles. 

The foot squads are usually in cover to hold my table quarters and provide fire support with their lascanons.  I use overlapping fields of fire to ensure full coverage of the battlefield. 

I hate Eldar and Tau being able to move out and shoot and then move back behind cover so I place or move my lascanon units to cover all blind spots behind cover.   I use one neo in the rhinos with 8 or 9 ini's.  IC's like the Champion and Marshall ride with the 9 man squads.  The ini's have bp's and ccw's with one pfist,and one flamer or mgun.  The one neo in each squad is fluffy and he is used in cc to be btb with enemy IC's so any extra hits in cc caused by that IC do not apply to my ini's due to the neo's different WS. 

I try and hit as many different enemy squads as possible when I assault to tie up their forces (particularly the shooty ones).  I try and keep my Chaplain and assault squad as a mobile reserve to engage countercharging units like the Death Co.  I always take the vow of hitting on a 3+/must assault and advance when playing BA.  I use the Champion to take out squad vet sergeants and weaker IC's. 

BT Defensive Tactics
This is how I prefer to fight if the scenario victory conditions allow it.  Even in Cleanse missions I play defensive for 4 turns and go offensive on turn 4 or 5 to take or contest table quarters. 

My force structure is usually the same with the 15 man crusader squad dismounted in front of my army with the other 15 man squad.  They form a solid wall like this '.'.'.'.'.'.'.' with 2" between the first and second rank and only a base wide gap between models on the same rank.  CCW and BP armed initiates in front with neo's and heavy weapons in the second rank.  I try and place them in cover or woods to get the cover save against incoming fire.  I give the crusader squad a lascanon and pgun instead of the fist and flamer.  I usually put two more 7 man squad armed with lascanon, brifles and pgun 4" behind this formation so they are shielded by it (5 ini's and 2 neo's each). 

Two rhino squads I keep mounted behind cover to act as countercharging or spoiler charging units along with the assault squad and Chaplain.  A spoiler charge is when a unit charges advancing enemy units before they reach the MLR (main line of resistance).  They also can react to deepstriking units that land behind my forces.   I place the Pred. and/or the crusader in woods covering main lines of advance for the enemy.  I use attackbikes with mmelta's behind the front line shielded by it.  If I have bunkers then I put the 7 man shooty squad in it (3 ini's with Brifles, 1 lascanon, 1 pgun, 2 shotgun neo's).  The whirlwind I place as far back as possible in woods if they are available with 6" of woods in front of it to shield it from enemy fire.

As the enemy advance I concentrate my lascanon, and mmelta fire on the rhinos and landraiders first, then the terminators,  assualt marines, and Death Co., and finally on the tac squads or fire support units.  I use the whirlwind first on scout squads, then light vehicles, then devastator squads.  When the rhino-less tac squads get into charge range I charge them first with my front line squads or with my counter charge units (rhino's and assault squads) so the BA do not get their charge bonus of +1S and +1I.  Hopefully the BA will have uncoordinated charges resulting from their raging and the loss of their transports on different turns thus stringing out their assaulting units.  My counter charge units can also take advantage of a weak flank to charge into the BA rear down one flank and attack his support units (devastators etc.). 

Like I said before I use the EC to kill vet sergeants and weaker IC's.  My Chaplain and Assault squad I use to countercharge his Death Co., assault marines and terminators that make it to my MLR.  Thay are also good at taking out immobilized LR's or crusaders with their meltabombs.  These tactics work well against all assaulty armies (BA, Chaos, Wolves, Orcs, Tyranids etc.)  They do not work well against shooty armies like Dark Angels, IG, Tau and Eldar.  Against shooty armies I usually use the offensive tactics.  I sometimes take the vow against psychers (Eldar, Chaos) that allows me an extra move (like infiltration) before my first move.


Your Brother-In-Arms
Marshall Hans Ulbrecht
1st Company, 14th Crusade (Epsilon Eridani)