as for gear:
A
good quality 20°f sleeping bag can work for all but the coldest days, keep in mind that this recommendation is mostly for men since woman tend to sleep colder so if you are one that is always cold drop it down 5 or 10 degrees. Also women fit different then men for obvious reasons. The sleeping bag is one area I do not recommend cheaping out on but that doesn't mean you need to spend $600 for the uber ultralight 900fill down model, try to keep you bag at or below 3lbs if possible for 20° bag it is doable for a 10 or 15° bag it would be tough.
Pros and cons for the different insulation
Down:
Pro
Warmest and lightest
Con
Useless if it gets wet
Synthetic
Pro
Stays warmer even if wet
Dries easier
Con
Heavy and bulky
Man made insulation are making leaps in bounds in the past several years so don't think you need to have down to be warm
All sleeping bag ratings are not alike, that means someones 10° bag is another companies 40°f bag, my mountain hardware bag is rated at 20°f but I have been as low as -18°f read the reviews and look at insulation thickness and you will be able to tell which rating is a comfortable at the temp rated and which is surviving at the temp rating
Sleeping pad, I use a cheap blue foam pad found at camping stores and walmart, you can use landau top foam as well available at your local car upholstery shop
For a backpack I do not recommend going bigger than 4000 ci, my standard weekend pack on 2800 or so again shoot for a goal of 3lbs
Tents, well I use a tarp only and bug spray, I have used hammocks, and tents each has the advantages and disadvantages
Stoves/Kitchens
I like jetboils and msr and esbit and... I still haven't found the perfect set up but again each has it's strength
Rain Gear, don't go cheap, well you can if you get Frogg Toggs but they are fragile but very lightweight and they breath really well, I like ponchos but it is personal preference
Whistle in case a bear tries to rape you
Compass, make sure you can read the numbers
Map of area don't rely on GPS it will fail you at the worst possible moment
Pocket knife, multi tool or fixed blade, I carry two
First aid kit
Sunscreen, sunglasses, bug spray
Bandanna (2)
That is a start