If you are tight on a budget:
Ariat Paddock Boots
Troxel or IRH Helmet
If you have a large budget:
TredStep Donatello Tall Boots
Charles Owen or GPA Helmet
I love the IRH helmets to school in, they are super light and certified to every standard. The more expensive IRH helmets are very low profile and kind of look like Charles Owen or GPA knock off, but for several hundreds of dollars cheaper. I know you mentioned paddock boots, but if you have the money I would definitely suggest a good pair of tall boots (with breeches) as they can help stabilize your leg better than paddock boots, plus they are more acceptable if you decide to get into showing. However, if you do get paddock boots make sure you also get half chaps to match.
Whatever you get for a helmet, try them all on as suggested. Some brands fit round heads better. Some brands fit oval heads better. Keep in mind if you get a fabric type helmet (instead of plastic on the outside) that they tend to collect a lot of dust and there's more effort involved, obviously, in keeping them clean. :)
The hardest part isn't finding what we need to be, it's being content with who we are.