Darn Tough Merino Wool - Lifetime warranty https://www.amazon.com/dp/B000XFZY1M/ref=cm_sw_r_other_awd_b1acwbTVY8DP8
ExOfficio Men's Give-N-Go Boxer Brief - it's like you aren't wearing anything, but they feel great. https://www.amazon.com/dp/B001M0MMYO/ref=cm_sw_r_other_awd_c3acwbRB21GMD
Columbia Silver Ridge Convertible Pant - quick dry pants. Used them for a 12,600ft summit https://www.amazon.com/dp/B0058YVMS2/ref=cm_sw_r_other_awd_i5acwbY7A5AKY
Duofold Men's Midweight - really warm and a good fit with enough room in the crotch area. https://www.amazon.com/dp/B003BSQOM6/ref=cm_sw_r_other_awd_a7acwbT8J26QY
Marmot Men's Precip Jacket - shells are always good. Make sure to go at least a size up from what you are so you can layer thick fleece or other warm clothing underneath. https://www.amazon.com/dp/B000FE013W/ref=cm_sw_r_other_awd_z8acwb764GN5F
Exotac polySTRIKER Fire Starter - always good to bring backups for fire. Fire Starter, water proof matches, Bic lighter,etc. Small and light. https://www.amazon.com/dp/B007K77W1Q/ref=cm_sw_r_other_awd_19acwbEBT3VN3
I also have a Osprey Talon 34 and an Atmos 50 which have been great, depending on the trip. For fitting of a backpack go to REI or other reputable store to get fit first for the proper size. Last thing you want is to buy a pack that's too large or too small and it's extremely uncomfortable to wear after long distance..
All items have varying quality with different brands, so you can find off brands for a lot of them, which is a plus for a beginner and on a budget. What I've learned though is its not always good to go with off brands for "super important" needs as your life or comfort might depend on it.