As said binx, cant mix daemons and marines anymore :(
so 2 seperate armies im afraid.
Daemons wise:
HQ choices:
bloodthirsters - fast moving, nice amount of damage, and tends to worry most people when facing one, allways a good shock attack against people who dont fight them too often.
keeper of secrets - even faster than the thirster at times, but doesent hit as heavy.
Gets the job done well though and is alot cheaper on points.
Heralds - Plenty of herald combo's out there, ranging from tzeentch heralds on discs for anti-tank (using bolt) to khorne heralds on juggernaughts in units of crushers.
Most will work well, but i would avoid nurgle heralds as they tend to lack punch.
Skulltaker - Strong, instant death on a 4+ means he can instant kill monsterous creatures which makes life easy)
in a chariot he gets more resilient, but cant join a unit.
on a juggernaught he can join units, and really boost thier power.
ELITES:
blood crushers - Simply amazing unit, 40 points per model and you have a very strong hard hitting unit that wont die too quickly, and can cause alot of damage.
2 units of 4 (each with a herald of khorne leading them) will provide some serious power, meaning you can push though defensive lines.
Hellblades also mean you can kill marines with ease due to ignoring armour saves.
fiends - Not very strong when they are being shot at, but they are very quick and have an insane amount of attacks, they can easily take out large unarmoured units with ease.
Flamers - Only really work well against armoured troops since thier breath ignores saves, meaning they are able to toast termies and the likes easily.
However, they are fragile.
TROOPS:
Daemonettes - Very fast and large amount of attacks, but tend to die due to being pretty weak on defence.
Bloodletters - not as fast as daemonettes, but alot harder hitting and they will last longer.
they also excel at killing armoured troops.
Plaguebearers - Allways take a unit of 10-15.
they refuse to die without a huge fight, but wont be able to hurt alot in combat.
Use them to hold objectives and they do great.
Horrors - not many people take them, but they offer a nice amount of shooting, and have the best saves of all daemon troops.
they are also pretty heavy on points, so not allways worth taking.
FAST ATTACK:
Screamers - Amazing anti-tank, they have meltabombs and move like jetbikes, meaning you should get over the board in a single turn and be ready to attack vehicles.
You wont need a large unit (3-5 at most) as they are cheap, but not too stable.
Try to keep them away from combat and allways attacking vehicles.
Flesh hounds - amazing models, but in the game they are very poor, they do look tempting, but they cost too much to make them effective.
so only really take them if you like them.
Seekers - the same as fiends really, easily killed yet can throw out an insane amount of attacks.
you may also have to make your own due to the models now being rare and pretty damn expensive.
HEAVY SUPPORT:
Soul grinder - your only option in the armie for a vehicle.
they are pretty tough, but being a vehicle they will be targetted early on, meaning it wont last the game.
you can take either attack, depending on weathwer you want them tank hunting or killing infantry.
I would take 1 with tongue simply for tank hunting.
Daemons princes - solid, strong and versitile.
Much like the herald you can change them to suit your need.
Khorne prince with might and wings makes a nice tank hunting monster.
Nurgle prince with breath and gaze allows you to hunt down units of armoured and un armoured infantry.
slaanesh prince is pretty weak
lol, so not worth alot.
Tzeentch prince is much like the nurgle one, but with less toughness and more shooting.
Allowing it to be anti-tank aswell as anti-troop.
allways take iron hide for them, it will make them survive alot longer so they can get thier job done.
Hope that helps, and ill apologise for any poor grammar