This is the second part of the Horde leveling , at this point you have to be level 25.  I know this guide is not as great as the famous Joana's 1-70 horde leveling guide, but this guide here can help a lot with the quests you can get and do as horde.

Horde Leveling 25-40

Your next zone will be Thousand Needles which is directly south of the barrens. You will stay here to approximately level 35 , so be sure to be read to stay in the zone for a while.

First quest :

>Message to Freewind Post<
-Bring the Urgent Message to Cliffwatcher Longhorn at Freewind Post (near A on the map)
Just after do >Pacify The Centaurs<
-Medium kill quest. Starts with Cliffwatch Longhorn in Freewind post.
-The Centaurs are found north of section A.

>Alien Egg<
-Hard kill/gather quest. Starts with Haga Lightninghoof in Freewind post.
-The egg is in the area on the ground , south of section A.
-The egg location wanders between three diferent locations.
When someone picks up the egg from one location, it respawns at one of the others.As a result, if you can't find it in one location, look in one of the others.With Cosmos [55,52] ; [52,55] ; [56,50]

>Serpent Wild<
-Easy find quest.Starts with Hagar Lightninghoof in Freewind post.
-Motega Firemane can be found slighty southeast of section B.

>Sacred Fire<
-Medium gather quest. Starts with Motega Firemane SE of section B.
-Incendia Agave can be found directly between the section A and B.

>Grimtotem Spying<
-Hard gather quest. Starts with Cliffwatcher Longhorn in Freewind post.
-Secret notes 1 , 2 and 3 can be found 31,36 - you'll see a very grim-looking totem at the entrance.

>Wind Rider<
-Hard gathering quest.Start with Elu , found in Freewind Post.
-Highperch Wyvern eggs are found directly below the section B marker.For the Quest of Wind Rider the Ramp is located not so much to the NorthWest but just West of Freewind Post. The ramp is located on coordinates 15,33 on your map.

>Hardened Shells<
-Medium gathering/kill quest. starts with Wizzle Brassbolts located in section D.
-Hardened Tortoise shells are drop in section D.Here

>Hypercapacitor Gizmo<
-Medium kill quest. Starts with Wizlo Bearingshiner , located in section B.
(Enraged panther can be found northern part of section B , Cage can be found at 22,24.)

>Load lightening<
-Hard gathering quest. starts with Pozzik , found in section D.
-Hollow Vulture Bone are drops found all over northern section D ~87.66.Here

>Salt flat Venom<
-Medium gathering quest. Starts with Fizzle Brassbolts found in section D.
-Salty Scorpid Venom are drops found all over Northern section D.

>Parts for Kravel<
-Easy delivery quest , start with Wharfmaster Dizzywig in Ratchet ( The barrens)
-Kravel Koalbeard can be found in section D.
>Wharfmaster Dizzywig<
-Back to Ratchet.

>Rocket Car Parts<
-Medium gathering quest. Starts with Kravel Koalbeard , found in section D.
-Rocket Car Rubble can be found all over the outskirts of section D.Here

>A Bump in the Road<
-Hard kill quest. starts with Trackmaster Zherin , found in section D.
- Saltstone Crystalhide , Saltstone Basilisk ,Saltstone Gazer can all be found scatter throughout section D.

>Martek the exiled<
-Easy delivery quest. Starts with Fizzle Brassbolts in section D.
-Martek the exiled's camp can be found in Azeroth , in the badlands.
-Follow the road south through the Wetlands.  Keep following the road through the Dun Algaz tunnels into Loch Mordan.Follow the road south until north of Thalsamar then cut SE until you hit the Lake. Follow the lake's shore to the south.When you reach the southern edge of the lake continue ... you guessed it ... south towards the zone edge. On your map there will be a dotted path leading into the Badlands. Kargath is in the NW corner. Grab the FP.
>Indurium<
-Part 2 , Stonevault Bonesnappers and Bashers can be found in the southern Badlands. Around here.

>Encrusted Tail Fins<
-Medium Kill/Gathering quest. Starts with wizzle Brassbolts , found in section D.
-Murkgill and Saltscale mobs can be found in northern Stranglethorn Vale in Zugsham , off the coast.There.

>Delivery to the Gnomes<
-Easy delivery quest. Starts with Kravel Koalbeard , section D.
-Fizzle Brassbolts can also be found in section D.Here

>The Rumormonger<
-Easy discover quest , starts with Kravel Koalbeard , section D.
-Krazek can be found in Booty Bay , on the southern tip of Starnglethorn Vale. Here.
>Dream dust in the swamp<
-Medium kill/gathering quest.Starts with Krazek.
-Speck of dream Dust is dropped by Whelps and Wyrmkin , who can be found all over the western end of the Swamp of sorrow , on the east side of the moutain.The mobs are a semi-rare spawn with an uncommon drop rate of only 20%, so make sure you have some time to hunt these guys. Almost impossible to do if there's 3 or 4 other people in the area on the same quest.
>Rumor for Kravel<
-Easy delivery quest. Starts with Krazek , Kravel Koalbeard can be found in section D.

-Desolace is your next stop.

>Hunting in Stranglethorn<
-Easy delivery quest. starts Roon Wild mane Southwestern part of section E.
-Hemet Nesingwary can be found north of the Grom'gol Base Camp.There.

>Centaur Bounty<
-Medium kill/gathering ques. starts with Felgur Twocuts , found in the southwestern corner of section C.
-Centaur Ears are dropped by Centaur mobs ( such as Gelkis) found all over Section E.

>Regthar Deathgate<
-Easy conversation quest. Start with Krusk not located in desolace but rather in the northern part of hillsbrad.
-You must then visit Regthar Deathgate located in the barrens.
Then : >The Kolkar of desolace<
-Easy conversation quest.Starts with Regthar Deathgate (The Barrens)
-Felgur Twocuts can be found , southwestern of section C.

>Khan Dez'Hepah<
-Hark kill quest. Starts with Felgur Twocuts , found in the southwestern corner of section C.
-Khan Dez'hepah can be found wandering the far eastern portion of section C.

>The Corrupter (Series quest)<
-Hard discovery/multiple kill quest. Starts with Maurin Bonesplitter , found in Section D.
-Takata Steelblade can be found directly between the section C and D.
-Flayed Demaon skin is a drop from burning Blade Mobs , found in southeast of section B.
-Shadowstalker Scalp by Hatefury Shadowstalker found in the eastern part of section A. [Part 2]
-Finally , Oracle Crystal is dropped by Slitherblade Oracle , found in northwestern section B.[Part 4]
-You must visit Takata Stellblade in between each successful item acquisition.
-Slay Lord Azrethoc and Jugkar Grim'rod : Lord A can be found on the corner of Section F , Jugkar in the same area. [Last Part]

>Hand of Iruxos<
-Medium kill quest. Starts with Taiga Wisemane , found in southwest section B.
-Demon Box is dropped by Demon spirit , found in northern Section C.

>Portals of the Legion<
-Medium kill quest. Starts with Taiga Wisemane , found SW Section B.
-Banish six Demon Portals in Manoroc Coven , first by killing the demon guarding each one.

>Catch of the day<
-Easy delivery quest. Start with Nataka Longhorn , found in section C.
-Jinar'Zillen can be found in shadowpret village. Just take the road south from Nataka. You need to take 10 Shellfish from the Shellfish Trap in the sea, and then talk the Jinar'Zillen to trade 2 Bloodbelly Fish.

>Kodo Roundup<
-Medium Gathering quest. Starts with Smeed Scrabbescrew , found in section C.
-Kodos can be found througout Desolace, mainly in sections B and D.

At this point you should be level 40. If not , you should grind out the remain xp off of Slitherblades in section B.They have good xp and drop the best sell loot.When you hit level 40 , you are ready to start your leveling instancing.