I am new to the forum. Been backpacking for 35 years and did my first solo that first year. I will echo what others have said about not finding people to go with. I have gone on 130 solo trips ranging from an overnight to 7 days in the Cali Sierras to begin with, Oregon Cascades, Idaho Sawtooths, Frank Church, Olympic Nat Park, Glacier National Park, Banff, Kootenay NP, Yoho NP, Provincial Parks around Nelson BC, and last year to Titcomb Basin and nummerous places in the Cabinet Mt Wilderness MT.
I would list what is important once I did this for for many years.
1) Trip planning, miles, elevation climbs, know your capabilities for miles and climbing
2) map reading and orientation, Carry a map, compass and altimeter/barameter for orientation and weather prediction
3) Bring sandals if stream crossings are shown on the map
4),Bear spray in grizzly country
5) Be familiar with bear food sources and recognize them and other bear signs
6) Rope and carbiner for hanging food.
7) Odor proof bags for all but the freeze dried foods
8) An ice axe or set of trekking poles (the last 10 years). Even if you don't cross snow, very handy for hopping boulders or limping home with a bum knee or ankle
9) keep your campsite and tent clean of any odors
10) Carry a comprehensive first aid kit that includes something to treat a sprained ankle or knee, and duct tape and wire for repairs to gear
Don't freak out and endure calmly the unexpected; those freaky things that happen late at night when wildlife is sniffing around your tent; or you run into wildlife on the trail; broken gear; lost food to wildlife; or injuries. See items 1-10, you have done everything right, you will survive the unexpected.
For 35 years, I only had a few mishaps. 1) I sprained an ankle getting out of my tent with loose boots one time, 2) sprained an ankle on a stream crossing, 3) Lost food to a flying squirrel (chewed thru the bag), 4) fell into a creek bed from 20 feet above by catching my campons bad on a boulder (dangers of a wide pack). Bloodied and bruised but walked out the final 5 miles. 5) Had both my boots half eaten by a mountain goat (wire and duct tape to repair) Keep anything with salt on it inside the tent, under the vestible is not good enough. 6) Deer stole my laundry for salt, 7)Deer stole two cameras/bag for salt (retrieved both) 8) Several times storms caused an extra day on a trip resulting in fish/berries providing the needed food, 9) Pack rolled over and fell on a red hot lantern (again duct tape and wire did the trick to repair a big hole). 10) Flat tire 2X at trailhead, and dead battery once. Now carry a unit that is a starter, battery charger and tire inflator, at all times
Now I have a wife that loves backpacking minus the ice travel, and use of ropes. I would always recommend a partner or two in grizzly country or rough terrain if you can find someone, especially as you get older