I definitely agree that it's the "forgotten" things that screw you over when you start budgeting. I always have a "Unexpected / forgotten costs" category and try and put £100 a month in, however now we have got better at not forgetting things we often have almost all of that to roll over to the next month.
With YNAB you do still need to tailor the categories to you though.
This is the rough way I have it set up under each group header:
"Everyday Essentials" - Groceries, Unexpected costs, DD essentials (used to be nappies, now not much really, anything essential bought outside of the weekly online shop), DD clothes and shoes, Transportation (trains, taxis, buses, parking), Toiletries, Cat litter & food, Petrol, Home maintenance (inc window cleaning, stuff like unexpected plumber visit etc)
"Everyday non-essentials" - Stuff for our twins due in Jan, House (this includes planned projects like decorating etc), Fun stuff (for me and DH usually empty haha!), DD Fun stuff (soft play etc), Family days out, Eating and drinking out, iTunes and kindle, Garden
"Savings" - a long term savings category, then 4 accumulators where I put maybe £20 or £30 a month in and spend from it as we need to: Christmas, DD birthday, Other gifts (wedding presents, bday presents for our nieces, etc), Car repairs (this covers tyres as well)
"Holidays" - Next holiday accumulator (may be paying off a holiday we've already booked, or just putting a bit extra in towards an unknown future holiday), Accommodation and transport (just used when booking), Spending while on holiday (only used when on holiday)
"Monthly fixed bills" - ALL our monthly outgoings that are the same each month.Don't forget any monthly charity DDs in here.
"Monthly variable bills" - for us this is just nursery bills and NowTV subscriptions, I just like having them separate.
"Annual bills" - Anything that isn't paid monthly. I work out the annual cost and divide by 12 and allocate that much each month. For us this is Amazon prime (£79 so 6.58 a month), Car service, MOT (note extra repairs are covered above), car tax, RAC, stuff like national trust membership, annual vet checkup, all insurances as we pay for them annually. Also DD's toddler music and swimming classes which we have to pay for termly are in here too.
The annual bills bit can be painful if you start doing this in December and your house insurance is due in February, say. But over time it all evens out and you're only putting say £30 a month away for it instead of having to find £360 in one fell swoop.
I've just realised we don't have a vet bills contingency account...
So that is all our joint account stuff but I also have a budget for my personal spending and some categories may be useful:
Haircut, Saving for Tax (if relevant; I earn a little money from self employment so have to do a self assessment), Exercise class (I have to pay termly), Clothes and Shoes.
Sorry for very long post but hope that is useful!