Tournament coming up, noob needs info!

So my GKs are 3-1 now and I'm going to a tournament Saturday. I have no false hopes of winning this but wish to be competitive. I'm new to warhammer in general and have only got to play against Blood angels and Sisters. Any tips in regards to defeating the other heretics?
Oh in case you are wondering heres my list (I am sorely lacing on models so what I have is all I have, just need tips on how to deploy against others)

GM blind, rad, sword sb
8 Purifiers all halberds, 2 incinerators
10 gkss psycannon, 2 swords, rest halberds, pb
10 termies, 1 hammer, 9 halberd, pb
Mortis
God hammer, sl, mm, sb, pb

GM and purifiers in lr to deliver them safely into assault range, terminators ds behind cover, gkss hide from the beginning, mortis hides and blows stuff up.

I know this is far from great but has done me well so far, and hopefully will continue until reinforcements arrive (aka, I can afford more gk goodness)
Thank you brothers

Sisters is a rare sight, no I really cannot offer too much advice there. BA however, can bring the Stormraven as a Flier. I don't see too many wasy to deal with fliers in your list. Also, altough not very popular, Furiosos are an issue.

I like the list, there is one thing that I would look at changing without changing the models that you have.
If you are planing on deep striking the terminators then you can look at changing the grand master to a Lib with a telieporter hommer.
If you do not like the lib then get some psychoke grenades on the G.M.
If your list is already handed in then I am to late.
In reguards to other armies, it is very hard to give advice on what to do with deployment against them, it all depends on the make up of their force and the mission being played.
Chaos: watch out for the forge fiend and the new flyer dragon, the dragon carries a ap3 flamer with torrent (12" range) and sole blaze (your guyes will stay on fire and continue to die at the begining of every turn) this will take out the strike squad (or over half of it) in a turn. The forge fiend is rude as well, normal weapons include 4 shot S8 guns (2 of these) and a plasma cannon on the head. Cultists that will deliver 4 attacks in close combat on the charge and come in packs of 20. Shoot them in turn 2 as they die form storm bolters.(there are other things that have to go down in the first turn)
Nids: Nids will normaly be deployed across the length of their deployment. With them I would look to give them first turn, why, because this would let you deploy against them on one flank. They will normaly be 24" away from your deployment zone, what you want is to deloy 30" away from them, they will move at you in the first turn, terrain will not slow them much and you want to keep them off you for as long as possible. Take down the big things first, start on one side and work your way across, and then work on removing the bulk of each squad and bringing them down to unit sizes you can handle. Beware of devil gaunts (termigants with 3 shot S4 guns in units of 20, 16" range) these will destroy units in a turn. Hormagunts can be taken down to unit size of around 7, they have no shooting and have to charge you to do anything so you can shoot them on the way in with overwatch.
Orks: Similar to nids but you want to destroy the transport vechiles early, if they have a big mek then it will normaly be in a battle wagon (armour 14 to the front) take it down early as he will have a kuston force field (cover saves to all), by destroying the force field it will slow the advance as the mek will be on foot and reduce the range of the field (uses the base of the mek not the battle wagon) then it is just a matter of shooting the green things.
Guard: get into combat as soon as posible and try to stay locked for their turn and then charge into the next unit. This is easier said then done as they will not nomaly hold for the second round of combat. Multi charging is an option but watch out for overwatch.
Tau: Simular to guard but with less firepower (it is stronger but not as much) and more movement. Kill suits first. This will reduce the movement of the army.
For your army I would be looking to kill anything with a melta gun (or similar) this is one of the main weapons for killing a landraider. Las cannons can do it but with only S9 you need a 5 to glance and a 6 to pen and you have to hit first, and then you have to do damage, so melta is your biggest threat.

On a second thought, I think you have too many points invested in the SS. Drop the Halberds, add a rhino 40 pts worth of weapons on an unit that will die easily is not a good investment. I'd also go for 2 Psycannons in the SS.

For the Purifiers I'm not a great fan of Incins. Instead I'd add Psycannons. On the Termies a good mixture of weapons is also good. Remeber that striking at different Initiative lets you choose how you die and who you can kill in CC.
Your LR is you friend so use it to advance and gain cover for your rhino and Dread. Since you only use one, the dread can also be a good contester. you can throw him on a small unit or a weak one for an easy kill. That way you can also avoid heavy fire, since he is your MVP for shooting.

Hope it helps!

All solid criticisms and advice, except I have no rhinos, psycannons, or other options at all. I'm new to warhammer and have not built up a collection of minis or bits yet. This is why I was asking for tips on dealing with other armies, not my own. Thank you for the help brothers. I do believe I'm dropping the landraider though. 2 games in a row its blown up turn 1.

What other mins do you have. Also do not get to worried about loosing the land raider all the time, your normal opps have some of the best melta in the game. Sisters can just pack it in.
A lib can help it surrive with scrouding. Rember the land raiders main purpose it to deliver the squad into hand to hand on turn 2. First turn you should move up 12", pop smoke, move another 6" in the shooting phase, cast scrouding and you have a 4+ cover save, and have moved 18" up the field. Next turn you move 6" deploy 6" and then charge. so an affective range of 30" plus charge.

maybe that's my problem, I'm not being aggressive enough with my lr.

No, if it is going down first turn it is normaly one of three reasons,
One, bad deployment
Two, bad luck
Three, not poping smoke in turn one and trying to shoot.
Or a combo of all three.
If you deploy in cover (not in it but behind some as you will normaly roll a 1 and imobilize the land raider if you go through terrain, I know I do) then you get some protection turn one if you do not get first turn (cover is now easier to get as only 25% of the vechile needs to be obscured). Then move up 18" turn one. If you do get poped turn 2 then you get out 6" in their suooting phase, makeing you 24" up the field, in your turn move 6", gives you 30" and then charge. (provided they did not blow it up and just wrecked it)
So provided you can make it last past turn 1 it is a good investment for delivering a unit.
Some will go for a Crusader as the want to sit back an shoot is not as strong and more models can be deployed, but if you are up against an army where you need a counter strike unit then the God hammer is better and brings heavier firepower.

Sounds like at least a fun list to run! All good advice too. Here's my two cents on the list and Gks in general:

Go with your personal preference on special weapons, I really haven't seen one that's ineffective on the field.

I haven't had a chance to play with my LR yet, as my buddies have temporarily banned it until they can find models and weapons that can glance it. But I imagine it makes a nice target on the field. I'd combine a couple of tips of advice from above, and stick the purifiers into a Rhino, and the Termies into a Stormraven.

Good luck at the tourney! I've only been to one, and my current record is 0-4 against Space Wolves, Chaos Daemons (tabled in 4 turns actually, but learned the most about how my army should work thanks to the friendly opponent), an Inquisitor packed GK army, and Eldar. Best two days of my life so far, can't wait for the next one!

What armies are they playing that they can't find something to punch through LR armor? I though every other army had stuff standard for tank killing.

Their armies do, but the models and options they have right now don't. Eldar and Tyranids to answer your question.

Sorry I am a little dumbfounded by a nids army that can't eat a LR. Every MC can double their strength so that is Str of 12 on average. Personally the first time I saw I hive tyrant or any other MC, I would rewrite my list bring a LR and shoot it with it with my first shot.

As for elder I know nothing about them.

My Tyranid buddy mostly runs genestealers and other CC models. He's been sitting out a lot of our weekly sessions to build his models. The first time he played us, he fielded mostly empty bases.

The Eldar player knows his army has some high powered weapons and models that could bring a LR down, but he's working on a S6 army list right now, and nothing he fields could touch AV14. He's having issues just taking down my Rhinos and Razorbacks, not to mention the Stormraven.