Start with the basics;
1. Mask. Buy local. Make sure it fits/test in the water if possible. Out of the water simply place on your face without the strap on and inhale slightly through your nose creating a vacuum-then stop inhaling. It should stay on your face for at least 5 seconds. Buy a low volume mask made with black silicone compound. Black may not be fashionable but Black assists your eyes to see better by not allowing light in except via the glass. Your pupils don't constrict as much-you see better w/less headaches. Personally, I'd stay away from multiple lences-three glass masks.
2. Bootys- Buy local. Again, try them on. Make sure they feel comfortable. If you'll be walking with them on get a pair with semi-hard soles. If your diving colder water(below 70 dF) I'd use 5-7 mm. Make sure they have zippers and are high tops-as compared to low cut. Mine are about 8" high. Get a pair with a fin strap clet-very important.
3. Gloves- Buy local. Make sure they fit! Don't settles for too large or too small just because your LDS has nothing else. Don't get them with zippers-I like the 'gauntlet' style in 5mm. Don't be afraid to buy custom-see wetsuit below.
4. Snorkle- Stay simple. No need for gagets, ball floats, etc. Don't get a snorkling snorkle, get a diving snorkle-there is a difference. Try to get one w/o a built on retainer-it will break. Get a simple 'double loop' type retainer. I like a snorkle that has a flexible hose attached to the mouth piece-it swings outta the way when I'm on SCUBA.
5. Fins- Compare prices on-line(ebay) vs. LDS. Try them on with your booties on! The fit should be snug, not loose/not tight. Look at Apollo bio fin, Tusa split fin, Scuba pro Split jet fins. Again don't settle for old fin technology. Stay away from add-ons like spring straps for now-KIS.
6. Wetsuit- This will be in my humble opinion your most important piece of equipment for beginners. Usually, those new to diving use the rental suits. Don't do it!! They will never fit and will never be comfortable and you will never be warm and you will quit diving with the mistakin belief all scuba is uncomfortable and cold. My advice-go custom fit all the way. The cost is comparable to many off the shelf suits. I use Aquaflite (aquaflite.com), but, simply do a google search or ask your LDS. Trust me on this one. Again, cold water means 7mm with hood(5mm). Consider a 7mm Fullsuit with a 5mm hooded vest. I dive southern cali, which ranges from 58-66 d. using a custom 5mm semi-dry fullsuit with a 5mm step in hooded jacket.
The rest of your gear I'd rx renting UNTIL you are more familiar with diving. Your see alot of gear out there, so don't be shy..ask. Please be aware of not buying all kinds of gear right away-overcome that temptation. Take your time and look around.
M