First you need to understand that bristle is amazing mainly against melee and short range attacking heroes such as: Faceless Void, Ursa, Templar Assassin and almost all the hard carries, because of his second skill Quill Spray and third skill Bristleback, that why you always have to the be the initiator in every team fight.
Can play solo offlane or with support.
Viscous Nasal Goo
Cast Time: 0.3+0
Cast Range: 600
Max Stacks: 4
Armor Reduction per Stack: 1/1.4/1.8/2.2
Base Move Speed Slow: 20%
Move Speed Slow per Stack: 3%/6%/9%/12%
Hero Duration: 5
Creep Duration: 10
Mana Cost: 30
Cast Time: 0+0
Base Damage: 20/40/60/80
Stack Damage: 30/32/34/36
Damage Cap: 400
Stack Duration: 14
Mana Cost: 35
Back Damage Reduction: 16%/24%/32%/40%
Side Damage reduction: 8%/12%/16%/20%
Damage Threshold: 250
Max Stacks: 5/6/7
Attack Damage per Stack: 20/25/30
Move Speed Bonus per Stack: 3%/4%/5%
Stack duration: 14
First things you should buy for laning are:
At level 1-2 you need to farm as much as you can, then you should buy Ring of Basilius for cheap mana regneration. Turn it off, if you don't - the creeps in your lane will push faster, because of the aura Ring of Basilius gives them.
At level 3 you have Quill Spray level 2 so you can start harass the enemies, but always keep mana for emergencies.
I love to upgrade Bristleback early, because it's really helpful in laning.
You might want to upgrade Viscous Nasal Goo on level 4, if mid gank your lane early it will be really useful for easy kill.
Bristleback has a low health regeneration early game, therefore you want to get a Ring of Health and only then Power Treads (obviously strength).
If you against long range heroes with magical damage conside buying Blade Mail or Pipe of Insight.
First thing you need to use is Viscous Nasal Goo(both in ganks and team fights), it slows the enemy and also reduce his armor.
You can use Viscous Nasal Goo few times on the same enemy, that will cause him to move slower than before and also his armor will reduce even more!
Don't tempt to go alone versus the whole enemy team, because even your survivability can't handle 5 vs 1 fight, wait your team first.
Most cases the game will end after 30 mintues, so I put Vanguard as a mid game item.
Vanguard gives you amazing blocking in addition to Bristleback.
If your team needs help teleport to them and help them, you are really sagnificant mid game, because Quill Spray deals a lot of damage.
Notice: In fights always use Quill Spray as a source of damage and only if you are close to the enemy - use your melee attack.
The next item you need is Octarine Core, which gives you amazing survivability and power for those reasons:
You can decide whether to buy Heart of Tarrasque or Radiance first.
I personally perfer Radiance because of the constant healing with Octarine Core, which increases your survivability, and also gives you nice damage even if you are silenced or stunned.
If the game hasn't finished yet, you might buy Assault Cuirass for more armor, attack speed (partially aura) and reducing your enemy armor by 5.
If you are against long range attacking hero, you will need Blade Mail, because of the Quill Spray doesn't damage him if he is far away from you ( Sniper, Drow Ranger or Skywrath Mage).
In case you are fighting against magical damage heroes such as: Invoker, Lina, or Luna you will have to buy a Pipe of Insight for magic resistance.
And if the enemy team ganks your team often, you might want to gank them too with Boots of Travel.
Crystal Maiden helps to increase mana regeneration Arcane Aura early game(when it's needed) and can help you get easy kill early game with Frostbite.
Bounty Hunter with his ult Track let you gank easier and get more gold from it.
Rubick with his passive Null Field gives you more magic resistance and really nice hero to lane with because of Telekinesis.
He is strong magical hero that slows and makes a lot of damage from long distance with Viper Strike and Poison Attack, so your Quill Spray will be ineffective, because of it probably won't get him because of the distance.
Enchantress has also long range skill Impetus that can't be reduced (pure) and has a slow skill too Enchant.
Invoker is another long range hero, who has a strong magicial skills and even worse some of them are disables, that will prevent you from using second skill Quill Spray.
Lion could really make you useless, he can drain your mana with Mana Drain and has two different disables: Hex and Earth Spike.