What do you wear for clothing now for dayhikes? You don't need more clothing, but some clothing like heavy jackets is better for dayhikes than for long trips. Where do you hike now, and what time of year? You should start there maybe. Alot of people say not to start with a bivy and tarp. I disagree. I would first recommend keeping it very simple, only adding a few items at a time. The rest I think you would be really better off if you figured out things for yourself. This is basically what I use...

Pack:
Golite Jam2
Blue foam pad 72"x28"x3/8"
20F rated sleeping bag
Army Surplus Gortex Bivy Sack
Rain Poncho/Tarp, 3 nails, 3/16" lines 2',3',5'
Opinel #7 knife
Kelly Kettle, 2 bottles, Mug, Spoon, Lighter, Matches, Candles
Map, Compass, Watch, Cell Phone, Whistle, Thermometer, FirstAid/Repair Kit

Clothing:
Trail Runners - least water absorbing pair I can find
Socks, wool, 3 pair - 1 thin, 1 medium, 1 thick
Skin Layer Bottoms - wool, silk, or poly 4-8oz depending on season
100wt or 200wt Fleece Bottoms - 8-12oz, must be least water absorbing
Hiking Shorts - light brushed nylon, with cargo pockets, and breathable
Flannel Boxers - the flannel boxers can be your one item of cotton
Wind/Rain Pants - lightest nylon you can find under 6oz
Skin Layer Top - wool, silk, or poly 4-8oz depending on season
Light/Medium/Heavy Wool Sweater - loose hand knit, felt resistant, weight depends on season
Wind Jacket - lightest breathable nylon you can find, like 4oz
Rain Poncho/Tarp - see Pack list above
Wool mitts, Wool hat, Wool neck/face tube, Brimmed Hat, Sunglasses
Carry a homemade hiking staff, just for fun mostly

Thicker in winter. Some stuff can be left home in summer.
Everything should be sized to fit to wear loosely all at once when needed.
Keep your Light/Medium/Heavy Wool Sweater on at all times. All else varies.

The only expensive item I might have bought right away would have been a top quality 20F rated down bag. If I hadn't bought the stupid overweight back that I did, I could have afforded it. The Golite Jam2 is a very good pack. There are others in that range, between 1 and 2 pounds, and between 3000 and 4500ci.