I have zero experience in backpacking and i have no knowledge on hiking light or whatever. But i've recently picked up a backpacking/hiking bug which led me to buy a number of a things, such as:

Kelty Coyote 4750 (blue)
Kelty Coyote 4750
Kelty Mistral 20 degree sleeping bag Kelty Mistral 20 degree
REI Half Dome 4 tent (tent)
Katadyn Pro Hiker Filter filter
Level 2 first aid kit (Custom made) blackhawk medical roll bag!
K-Bar Becker Knife K-Bar Becker Knife
(Lights)Fenix LD20/ Petzel Tika plus 2 and Petzel Tika XP2
Basic Hiking shoes from Big 5
Jet Boil Flash (with a number of mountain house foods and a Maxpedition 12x5 water holder that fits perfectly)
GSI Dualist Cookset
Fire starter Fire starter
Bear Spray
(Looking for a good sleeping pad and
looking for pants (or convertible ones) and i already have a number of wicking material from my running gear. I can substitute my hiking layers with road cycling clothes too, such as: Craft craft, Giordana Giordana, and Arctic guard (thermal wicking material).

I've only hiked in Yosemite (e.g. upper falls 5-6hr round trip) and thinking to expand my backpacking,hiking, and camping skills to 2-3 day trips. What are some good tips to give to a first time multi-day backpacker?

Excited to be a member and outdoor enthusiast!

Background:
5'11 175lbs
Tennis athlete for 13-years
Hobbies: Snowboarding, trail running, half-marathons, road cycling, and poetry?