My advice to newbies:
Start gradually. Let your body adjust.
Height matters. Try different keyboard and screen heights to suit your wrists and neck. Try all your different-height footwear.
Furniture doesn't matter. Start with boxes, shelves, whatever. Confirm you like it, then buy or build furniture.
Move. You can get tense and cramped while standing just as easily as sitting. Try these:
- Shift your weight, move your legs, raise your head to people-watch.
- Intentionally store some stuff you need *behind* you, to force movement.
Don't just stand.
- Raise one foot on a footstool or a box. Alternate feet.
- Kneel one leg on a bar stool. Swivel your leg mindlessly. Alternate legs. (Don't sit on it, kneel!)
Be reasonable. Stand only as long as it feels good. Alternate sitting.
Be smart. Always invite your boss to sit when she visits.
And most importantly:
Try it.