I'm throwing a birthday party for a two and three year old, need ideas for decorating.?

i am throwing a birthday party for my children. they are two (be three in October) and three (be four in August). would like some decorating ideas. i've done the invitations myself, already got the cakes ordered, and have the place for the party reserved. it's nothing bug just some family. there will be a few kids there (possibly 8 no more than 10). having the party at a local pizza place (pizza plus). our daughter loves tangled so we are going with a tangled cake and theme for half the party and our son loves Toothless off of How to Train our Dragon, so his half is going to be that kind of theme. As i already stated. we have the cakes on order already. i'm not looking for anything all out expensive just some ideas tht are budget friendly but will still look good. any help is appreciated. thanks in advance.