Are you on a time limit? If not, then you can go with more of a horde army -- an option not available in tournaments due to time limits set on games.
I am going to assume that you are not on a time limit -- which leads us to the next stage...strategy. This is the best advice I've ever seen on making orks work.
Orks can do anything that any other army can do and do it better than they can. However, they cannot do everything that any other army can do. Make sense? If you make an ork assault army, they'll out-assault any other army in 40k. If you make a shooting army, you can outgun IG or Tau. If you
go foot-slogging, or mechanized, or kan-wall....all those options make you a completely awesome army, but there's a catch. You can only do one of
them at a time with an army list.
If you combine a mechanized and a foot-slogging list, you're going to lose. If you have part assault, party shooting, you're probably going to lose. Your strength is in being able to pick something and be completely awesome at it. So before giving you advice on where to go next with your army, you need to pick a theme and build around it. If you want a bike army, or a shooting army; an outflanking army, mechanized, assault, figure out what your playstyle is and start building your units and armylist around that idea.
THAT is the strength of Orks.
Based on your models, this is what I would run as your army. This is a horde army with 150 models on the table. This is 1995 points, and I'm sure you can tweak it to your liking.
HQ 210 pts
[105] Warbosses w/
PK, Attack Squig, 'eavy Armor
[105] Warbosses w/
PK, Attack Squig, 'eavy Armor
Have one warboss join Snikrot's crew and bring him from behind the enemy. Snikrot uses Ambush, not inflitrate so your warboss can join in his fun. This will not make you friends -- but if your playing a highly competitive player they will respect you. Expect to play an additional phase -- the argument phase -- when you spring this on him.
Elites 265 pts
[265] 15 Kommandos w/Snikrot.
Use 2 burnas in here. Use a normal boy for your last kommando to fill the squad to 15.
Troops 935 pts
[230] 30 Shootas + Nob w/
PK + 3 big shootas
[225] 30 Sluggas + Nob w/
PK + 2 big shootas
[245] 30 Sluggas + Nob w/
PK + 3 rokkits
[235] 30 Sluggas + Nob w/
PK + 2 rokkits
We are using your rokkits and big shootas here to allow you to bring 30 man squads. It's not ideal, but you need to try and bring 4 squads of 30 boys. Looking at your models you can make it work if you use some heavy weapons. You might also just use some
AoBR nobs as normal boys to fill up these squads -- you can use that to save 60 points if you can find a good spot to put them.
Fast Attack 585 pts
[180] 4 Deffkoptas w/Twin Linked Rokkits
[225] 5 Deffkoptas w/Twin Linked Rokkits
[180] 4 Deffkoptas w/Twin Linked Rokkits
These are your main
AT. Turbo boost them and use them to take care of vindicators, whirlwinds, dreadnoughts, etc... These models are awesome for
AT, as twin linked rokkits have a 1/3 + 1/3 chance of hitting -- some of the best shooting in your army.
Strategy
Missions
You have 4 units you can use to take objectives, being annoying hard to kill while in cover. Utilize this to your advantage. You only need to hold more objectives than him, so either keep him away from your objectives and use your koptas to contest his starting at turn 5
In
KP missions, you give up 10
KPs. You should do well on these missions as its hard to completely wipe out 30 ork squads. If your up 3
VPs and its turn 5, just take your boys and go to ground for the last turns in cover. Boost your bikes to the back of your lines to deny
VPs. If your opponents are competitive players they might call you cheezy but they would do the same thing.
Deployment
The mission type depends on your deployment. In dawn of war, don't fall into the temptation to put 61 boys in the middle of the board. They will be stranded from the rest of your army. Instead put one or two models in a congo line to the center -- this pushes him back, and keeps your models close to your mob.
A warboss joining Snikrot is just mean. The worst part is that he can leave the squad during the movement phase and tear up another squad/tank by himself. With 6
STR 6 hits on the charge, I've used snikrot to rip open tanks, tie up oblit squads for the game, its very effective -- and will destroy whirlwinds if required.
Tactics
Remember that your army may move slowly, yet can burst with surprising speed. When you Waagh, you can move 6", Fleet 1-6", and Assault another 6". On the turn you waaagh, use this to your advantage and surprise him. Even when not waaghing, running can really make those boys move faster than expected.
If you have rokkits in your boyz squads, use them on rhinos. If you can't get to the crunchy marines inside, thats a great way to crack a tank. Hell, if your big shootas don't have anything better to fire at, use them too, you might blow off a weapon or keep it from moving.
Your main tool to destroy his vindicator, dreads, and whirlwinds are your koptas. Use the turbo boost at the start to keep them alive. He will probably fire the whirlwind barrage that does
STR 4 and ignores cover at them. Thats fine -- its
STR 4 AP5, so your koptas will be fine. He wounds them on a 5, and you get a save.