Hi just wanted to seek some advice for my character. 

I'm a lvl 3 Goblin Barbarian with Ancestral Guardian (Stats: STR 18, DEX 13, CON 16, INT 10, WIS 13, CHA 12 - thanks to Tasha's custom)

I'm utilising a halbred with reach, as well as nimble escape to hit and run with ancestral protectors.
(*edit* my DM allowed me to waive the heavy weapon disadvantage ruling for my goblin barbarian *edit*)
My party is kinda squishy so I do plan to rely a lot on ancestral protectors + spirit shield(at barb 6) to help them out as much as possible, while doing the whole hit n run gimmick. 

Moving forward, I just wanted to hear any thoughts you might have as to what to do next with my build. 

My thoughts moving forward are:

• get polearm master feat at lvl 4 (not entirely convinced about this yet)
• get barb to 6 for spirit shield
• multiclass to fighter to get echo knight (any fighting style recommendations?)

Would you recommend something different? (Like getting my STR to 20, or getting GWM/Sentinel?)

Thank you for your time and any suggestions would be greatly appreciated <3

I think Echo Knight/Ancestral Guardian multiclass actually synergizes pretty well, both in features and thematically, since you can flavor the echo to being just one particularly tough spirit.

Out of the fighting Styles available... it's not exciting, but I think the Defense style is best for you. Just a solid +1 to Defense pairs well with Ancestral Protectors, since it basically forces one enemy to target you with their attacks, so making sure your defense is boosted will help prevent them from hitting you.

I would actually recommend against Polearm Master with this build because you're going to want to keep your Reaction handy for Spirit Shield, and if you're multiclassing into Echo Knight you'll have a better bonus action attack you'll be able to use at higher levels.

Thanks for the response!

So for my barb at level 4, would you recommend I get stats or another feat?

The Defense fighting style only functions while you're wearing armor, so it's not a great option for a barbarian.  Superior Technique or Blind Fighting would probably be more useful.

With the stats shown, I'd go with Slasher at level 4 and bump your Dex up to 14.  That gives you +1 AC and the ability to slow down enemies when you hit them, which plays well into your defensive role- keeps enemies from being able to run down party members as easily and encourages them to stop and fight with you instead.

Thanks for the insightful response!

Yeah now that I think about it, pumping dex by 1 helps a lot for the extra 1AC. Just wondering if squat nimbleness (for the extra 5ft movement) or skill expertise (for expertise and additional skill prof) would be more useful than slasher (but I must admit the -10ft movement is also quite juicy). 

And blind fighting definitely does sound good because my party does have a ranger that has a penchant for casting fog haha. 

Skill Expertise can always be fun if there's a skill you really want to be able to be good at.  Squat Nimbleness I'm less impressed by, as a goblin you've already got a base speed of 30 and at 5th level a barbarian gets +10 movement and speed increases offer diminishing returns- the faster you are, the less valuable another increase to your speed becomes.  And I strenuously recommend going to 5th level before you multiclass because you really, really want Extra Attack as fast as you can get it.

Halberd gives you disadvantage on attacks as a small race, so don't use that. However, that does not mean you should ditch the bigger dice. Take a Lance instead. It's a d12, has reach and is not heavy. You'll need both hands if you're not mounted, but you planned on using both anyhow. You'll have disadvantage on attack rolls against enemies within 5', but you can disengage as a Bonus Action every turn to safely get out of the 5' reach thing. Notice that unlike ranged attacks, only the target's position matters, not any hostile creature.

You can then choose Piercer for the feat at level 4 to round up Dex, reroll bad damage rolls (very good for a d12) and roll extra damage on critical hits (amazing for a d12). 

This will mean you can't rely on your BA for anything else really. You usually won't care about it for round 1 when you rage, since you might not be in the enemies' reach yet, but it means multiclassing into Echo Knight wouldn't work. Consider a different Fighter subclass or just straight Barbarian. I would stick to Barbarian, but some Fighter subclasses still work well. Champion for even more of these nasty crits, maybe.

Quote from Beardsinger >>

A huge issue here is you are using a halberd. As a Goblin all of your attacks with it will be made at disadvantage due to your small size. It’s just not worth it. You are better off going longsword or battleaxe and shield. 

 As a small race, you'd have to use a versatile weapon like a longsword or battleaxe two-handed.  To use a shield you'd need to switch over to something that's not versatile, like a war pick or morningstar (though as those are both piercing weapons you'd want a different feat than Slasher).  If you want a Reach weapon, you're stuck with using a whip.

Could have sworn I saw it.  Might be thinking of older rules editions.  I pretty much never play Small characters so I'm not as well versed with the rules as I could be.

Heavy. Creatures that are Small or Tiny have disadvantage on attack rolls with heavy weapons. A heavy weapon’s size and bulk make it too large for a Small or Tiny creature to use effectively.

From PHB Weapon Properties section.  Now, on that topic, I play a Halfling Barbarian and my DM has hand waived the rule.  That's a table rule and DM purview entirely.  I like it, as it helps eliminate the slight damage dip I would face.  Thematically, I absolutely LOVE Small races being Barbarians.

Ah I'm sorry but I forgot to mention that at the start of the game I asked my DM about this rule, and he said he'd allow me to play my goblin barbarian without disadvantage on heavy weapons. 

So yeah no issues with using halbred. 

Regarding skill expertise: I actually have not much idea of what skills are more useful than others (apart from the basic perception and more athletic things my barb can do haha). 

But noted on the squat nimbleness and getting to level 5 first before anything else :)

I like Ancestral Guardians with high AC.  Drawing attacks to you, then having high AC, and then halving the hits that do get through makes you really hard to take down.

That is why I propose using a shield, and not using reckless assault on every attack.

Using a 2 handed weapon is 1-3 extra damage per hit.  +2 to AC from a shield is much better than that.  

If you fight spear and shield, you can even use polearm master.