I was wondering if anyone had any commentary and advice on the difference between starting with 3lps and 4lps. I get that 4lp characters are a bit more competent, but how does this affect play and the feel of the game? I’ll make the decision between 3 and 4 lifepaths with players who’ve never played BW, and some of whom are new to tabletop rpgs - how can I explain the difference to them? How does it affect the game if you allow a mix of 3 and 4 lp characters?
Thanks in advance 
A lot of it is how old and “established” you want your characters to feel.
3 LPs is actually pretty strong. You can build Squires, Augurs, Rogue Wizards, Doctors, Striders, cagey Criminals, et cetera. Characters will tend to be around 16-23 and reasonably well-trained, with just enough room to cover a broad base or really specialize in some focus area. But you’ll probably start out feeling like you’re missing something – a few more skill points, a stat you wish was just a bit higher, some reputation or trait you really wanted. That’s fine. It’s good. It gives you a nice clear thing to work towards, right away. (“I’m poor and I really need X right away” is a great basis for a first-session Belief, in my experience.)
You can expect to fail a good bit, but you’ll end up raising a lot of skills quickly, and, often, baked into your character is the sense that you can afford to fail a little – narratively speaking, I think we’re very used to seeing a squire trying to earn a knighthood, or a journeyman mage with new power, a brazen teenage criminal, &c. screw up, take their licks, and keep on marching; so the setbacks that can accrue just make their relatively rapid development seem fitting.
4 LPs, if you’re picking the powerful and goal-directed ones, makes you a solid, serious contender. You’re like 24-32. You might have been practicing your craft or rising up through the social ranks for a decade or more. If you take a lot of social/intellectual lifepaths, you can manage to have a B6 in a mental stat without totally tanking the other one. You have enough resource points that you can afford a home, a business, your own street gang, some serious military gear, or even some truly advanced spell knowledge. You should still feel a pinch in places – Burning Wheel doesn’t like to give you characters that already have everything they need, and IME you should generally avoid playing those characters when you do find ways to create them, because the motivation to turtle up is just so much higher – but you’ll start out with a lot you can throw at any situation.
If their lifepath skills already tie into the situation well (i.e. you’re not playing a middle-aged farmer who suddenly has to go hunting vampires), these characters are great for plunging into high-stakes stuff. Because they’re powerful and resilient, IME, you absolutely have to make sure they’re deeply motivated and facing worthy opposition from day zero. If you let them sit around to grow complacent I think there’s a risk of such characters becoming a overly cautious and fragile much faster than 3-LP protagonists would.
Thanks for the commentary! From the sounds of it, with new players it might be good to start with 3 lps - that way there’s obvious things to work on while we get into the advancement/artha/BIT cycle. If playing with mostly 3 lp characters, would it be acceptable to let a player start with 4 lps if it’s really necessary for their character concept, or would it create a bad dynamic round the table? Thinking of things like the Thinker or Scholar lifepaths, for example, which can’t be got to in three steps. (except, brilliantly, you can get the age requirement for Thinker in 3 lps only (as far as I can tell) by being the village idiot. my love for this fact is beyond words)
I don’t think it’ll be a problem.
As long as the characters have distinct BITs, they don’t tend to overshadow each other that much even if multiple PCs exist in the same mechanical “niche” (like a Squire and an older Knight) — you end up with a mentor/protege dynamic, at worst.
And with someone like a Thinker or Scholar especially, I figure many of their skill points are likely to go to abilities that grease the wheels for the rest of the group to get to the juicy conflict faster.
On the other hand, I think it’s good standard Burning Wheel practice for the player to consider instead amending the concept and building a 3LP not-quite-there version of the character who, say, hasn’t yet become a full-fledged Scholar, or who has just joined the Scholarly circles and hasn’t been around long enough to acquire the knowledge, respect, and lifepath benefits that a Scholar of several years would have.
The point of this, of course, is that it is another way to start that character off with something to work towards. Maybe they’ll have a Belief about earning recognition, or gaining the respect of their intellectual peers, or about finally learning History or Philosophy or a Foreign or Ancient Language. Or about proving their worth (finishing their thesis? 
) and being admitted to the scholarly academy. Something like that.
Thanks! Really useful advice - I think I’ll go with 3lps and let the ‘incomplete’ characters drive the early game.