Party for 4 year old - how?!

[TexMex]

So far I've got away with just having cousins round for a tea party, but now she has been to some friends 4th birthday parties DD thinks it must be her turn for one so I'm giving in!

So I've booked village hall, food sorted. What else do I need to do? How early do I send out invitations? Are party bags a must? Was going to make sure I have tea/coffee and biscuits for parents too. Any tips or better still a list I can follow would be great!

If the hall is big enough and they will let you, then you could hire a bouncy castle. That would keep them entertained for ages. Our local village hall organiser lady agreed to that when I asked about it.

My dd just had her 4th birthday party last weekend. We used a leisure centre which had a huge bouncy castle in one room and another room for the party.
Guests arrived at 11 straight onto bouncy castle for an hour, then into other room for lunch.
I provided tea, coffee and water for adults
I got paper lunch boxes from ebay, all different colours and each one had a carton of juice, a roll (half ham, half cheese), packet of Pom bears, satsuma and choc chip cookie (home made from bbc good food recipe off tinternet) inside. These were put on the tables whilst the kids were on the bouncy castle along with a plate of houmous and veg sticks per table (approx 8 kids per table)
After lunch we had pass the parcel, musical statues (used projection torches from poundland as prizes) and a pinata before singing Happy Birthday and cutting the cake, I made a rainbow one that was pretty much identical to this one I am not a natural baker but it must've been easy as it turned out really well.
Everyone got a piece of cake, a book (I used the book people for their 10 packs of books and it worked out at under £2 a book) a party blower and a bouncy ball (they were supposed to get those amazon finger lights but they only turned up this week-I'd recommend them though just leave at least a month if you order!) in their party bags (just small white paper bags from ebay).
I blew up a load of cheap balloons and had an huge 4 helium balloon.
It was really well attended (25 kids) and all the kids seemed to love it. The books were really popular with the parents too.
It was loads cheaper than a soft play and I'd definitely do it again.
Our invites went out about 3 weeks before the date.

dingalong and salvadory some great ideas there, thank you. One thing I'm struggling with at the moment is pass the parcel, what to have as the "prize" and also nowadays there is something in each layer for each child isn't there? In my day it was hardcore and you didn't get anything until you got to the last "prize" (cue lots of tears!) but it leaves a headache with what to put in! Any ideas? Otherwise plans coming on nicely thanks to all the great ideas on here.

We put small packets of haribo in every layer. Could do bangles, rings, bubbles if not keen on sweets?