Since the old guide is a bit broken and kinda useless i decided to write my own guide for this.The things we need for this task are:
* WoW Model Viewer any version

* Photoshop editor
* Tallis
* Blp to Png converter
First we will start by opening WoW Model viewer and creating our creature

Go to Characters->The Pick the race you want for your own creature
Next thing we gonna do is add equipment to it or well we can set his appearance: skin, hair, facial features and so on.
In this example i have chosen worgen male.

And chose all equipments what do you want him/her to have.

Now before i export it I usually make a list and write displayids of the items i have chosen for his/her's equipment.
Next thing we need to do is to export a texture for our creature but before that write in a notepad displayids of the following items type: Shoulder,Cloak ,Weapons,Helm.
And Set them to none.

Now go to File->Export Model -> 3DS
and save it.You will see a .tga file open it in photoshop.Sometimes Model Viewer bugs when you export certain races but i have found a solution for it.

If you want to export or to create for example BloodElf but model viewer is not exporting it right. simple export any other race then search in bakednpctextures for a texture of already existing bloodelf and change heads! (Will explain this method later)
Then save it as .png

Now start Tallis and open CreatureDisplayInfo.dbc and CreatureDisplayInfoExtra.dbc
Those 2 we will need to edit.
In CreatureDisplayInfo.dbc you are interested only in 4 fields.
field #0 - DisplayId
field #1 - Modelid
field #2 - Soundid
field #3 - ExtraDisplayInfo
-In field1 you need to add exact modelid of your creature: If you have chosen Human for your base your modelid would be either 49 or 50 depending on the gender.
In my case i have chosen Worgens which are custom therefor my modelid is also custom.If you dont know what modelid is for your creature you can always find it out by going to CreatureModelData.dbc and first field represent your modeldid
So for my worgen modelid is 5005(male), 5006(female)
Moving on.
In field#2 i leave it blank and in filed#3 i put a unique number such as for example 21407.
And this is how should it look when you first edit CreatureDisplayInfo.dbc

Now lets start editing CreatureDisplayInfoExtra.dbc
But first to define fields:
field0 - id ( The number from field3 in CreatureDisplayInfo - in our example 21407)
field1 - race id of your creature in our example again it is my custom value and it is 26
field2 - gender 0 male , 1 female
filed3 - Skin Color
field4 - Face Type
field5 - Hair Type
field6 - Hair Style
filed7 - Beard Style
field8 - Helm (displayid)
field9 - Shoulder (displayid)
field10 - Shirt (displayid)
filed11 - Chest(displayid)
field12 - Belt (displayid)
field13 - Legs (displayid)
field14 - Boots( displayid)
filed15 - Rings (displayid)
field16 - Gloves (displayid)
field17 - Wrist (displayid)
field18 - Cape (displayid)
field19 - CanEquip ( 1 - if you do .morph in this creature you will be able to see all other of your equipments , or 0- for not)
field20 - Texturename
Now all these informations you can gain from Model Viewer.
Skin as you can see is 0
Face type = 1
Gender = 0
Hair color = 3
Hair style = 1
facial feature = 4
Helm - 59184
Shoulder - 60505
Shirt - 0
Chest - 59128
Belt - 0
Legs - 0
Boots - 0
Braces - 0
Gloves - 39644
Wrist - 0
Cloak - 58988


Now save those .dbc files and close Tallis.
Now drag your saved .png files onto blp converter and convert it to .blp

Now it is time to patch it all.
Download Ladik MPQ
and create new patch
we will need first to create new folder call it DBFilesClient and put in there CreatureDisplayInfo.dbc and CreatureDisplayInfoExtra.dbc
Then Create another folder name it Textures-> Inside it create new folder name it BakedNpcTextures and in that folder place your converted .blp file.

Now On TC there are sometimes problems when you are creating new creatures especially with new models, keep that in mind you need to fill 2 tables creature_template and creature_model_data
Now place CreatureDisplayInfo.dbc and CreatureDisplayInfoExtra.dbc in your server dbc folder too and if you have done everything right your creature should appear fine
