Key point of this strategy is to be fast, it might require quite a bit of macro and multi-tasking.
At the start of the game, there are 5 important things that you need to do(At the same time):
1. Spam workers around lordaeron(Mostly from the deathknell and the Sepulcher) to chop lumber, this strat requires a lot of wood.
Do the improved bows research at the war quarters(very important for creeping)
2. Stop trolls from getting gundrak
Drag your starting battle ships to this coast(Don't be so close otherwise he can attack your ships with land units)
and stop him from getting to NR by boats.
Creep the elf cp above the healing fountain with the starting units there to get extra income too.
Build some extra battle ships if you have extra gold.
3. Rush NR with workers next to Deathknell
You will need to train 3 workers from this base, get them into a boat and drop them there.
Use the 2 abominations to draw the attention of the creeps and let the workers get through
Build a few barracks(up to your choice if you prefer casters, personally I would go for ghouls and archers plus 2 or 3 deathguards because they dont require much apm there) and a town hall(in case you need more workers) here:
Ideally Purple is currently doing storm peaks at the moment, if you want to be safe, move to the south for a bit(next to the goldmine terrain). Creep with the units you train from these barracks.
After you get maybe 20 or so units there, purple might have finished storm peak, go there and spam towers and barracks to stop him from moving out.
If he chose to go for the nexus part first, go take storm peaks with your archers and 1 or 2 siege units(They can reach it from the bottom)
After that, expand in every direction with units to get gold, retreat to your towers if you encounter purple's full force
4. Creep to the south of The Sepulcher with Faranell force and towers
Grab the starting units except for faranell to creep the cp at fenris keep.
Level up Faranell W and E, build 7 to 9 towers and upgrade them to Ballista towers. Most important thing is the tower at this position(the selected one,shown in the picture)
This tower allows you to reach the shadow tower around shadowfang keep and lure the creeps to attack you.
Keep in mind that you need to summon abominations and use them to tank. The ballista towers are squishy and they can be easily destroyed from friendly fire splash.
Arugal will keep summoning worgens untill he uses up his mana, so this is a good resource of income at the start.
5. Take Scarlet Monastery and Andorhal with Sylvannas forces
Take every unit you have in undercity and go for Scarlet Monastery(Just aim the main building after you take down the 2 cannon towers), you will receive many good units.
After you get that, go to andorhal and take it(Purple would either be fighting Red or in NR). Start spamming towers and build a shop as you attack andorhal(Don't train much base units against Red, they can massive aoe that can melt your archers easily).
Get a tp scroll on sylvannas in case you need to go NR.
Aim casters with your towers, then scarlet destroyers(Keep spamming towers if Red is still there).
Charm meaty units like knights and abominations with your elites.
Try and take scolomance with your bonus units from Andorhal, make sure a hero is here to pick up the items and tome.
If you successfully put out all these, you should be unstoppable in NR and Lordaeron. Don't forget to get upgrades and Apothecary plague when you have gold, be sure to be there when LK comes out so you can aim him down instantly.
Good luck and have fun.