Well, I'm just gonna expand a bit on the items that you have listed first...
Hat: Headwear is unimportant. Whether you're wearing a bandana, beret, cap, boonie, or helmet, it's really a matter of personal preference. Choose whatever, but usually it's best if it matched the rest of your BDU. And of course, if you're playing in winter, it stands to reason that you wear something that will keep your head warm since you lose the majority of your body heat through your head.
Mask or goggle: In some cases this is a choice, in others it isn't. If you play airsoft on a paintball facility, their insurance requires paintball rated goggles. Even ANZI-rated ballistic goggles won't be accepted. Mask is generally a matter of choice. I haven't seen too any people wearing them outdoors, but I some people like to wear them indoors for CQB because it protects their teeth and faces. If you play elsewhere in private fields or airsoft fields, then usually ballistic goggles are accepted and the best choice. Some will allow ballistic glasses, but sealed goggles are much safer.
Jacket / Pants (BDU): If you're not playing on a team, it generally best to start with a BDU that actually blends into the area where you'll be playing. CADPAT TW, MARPAT or US Woodland or Olive Drab are usually a good basic place to start and will work well in Canadian forests
Vest: You need a vest to carry your stuff. You need to carry extra mags, and often other items in the field, This is the important part of your gear. You want something that's durable, versatile and adaptable. It's preferable to get something that's modular (MOLLE) so you can switch pouches, as necessary for different loadouts. It also doesn't tie you to one specific gun. If you need to carry MP5 mags instead of M16 mags, you can swap pouches easily. Also, try to get this in either olive drab or coyote brown, as those two colors will work with almost any other camo pattern, which will give you options down the road.
Boots: Get good boots. Make sure they're comfortable ad provide good ankle support. Nothing makes for a miserable day in the field like boots that hurt your feet. Get decent ones. Your feet will thank you.
Gloves: If you get some, get some that won't compromise your finger movement. Make sure they give you enough dexterity to operate your equipment properly.
Other good things to have are as mentioned by others:
Knee pads - I see these as very important, probably because I'm older. Trust me. Be kind to your knees. You'll be happy you were in 20 years.
Radio: A radio is nice to have. You don't need to spend a fortune on it. Useable FRS/GMRS radios are fairly cheap, although keep in mind you get what you pay for. If possible, get one that comes with an earpiece and mic so you can have it accessible all the time. A tactical headset is better. There are some replica ones available for reasonable prices too.
Hydration: Whether a canteen or a camelback, if you're playing outside in summer, hydration is a necessity. I like 2-3 litre camelbacks and have them attached to the back of my vest. They carry all the water I need for a day game and I don't have to go refill.
This will give you a good, basic starter setup that both useful and versatile. Once you've played a few games, you'll know what you need to add to your kit to make it work for you.
Last edited by Crunchmeister; February 28th, 2009 at 00:21..