Tips and Tricks and things you may not know
Hit F10 two times to hide your UI for taking screenshots of your work. (Then once more to bring it back.)
There is a worldwide decorating chat channel. Just /join antonia_bayle.homeshow from any (non-PvP) server.
Use Shift + mousewheel to resize object (use Alt + Shift + mousewheel for smaller increments).
Use Ctrl + mousewheel to levitate objects off the floor (use Alt + Ctrl + mousewheel for smaller increments).
Bury a small single candle inside an object you want to light up.
Try using the backs of paintings for panneling.
Rugs, benches and wall shelves make great stairs!
Don't forget to feed the hungry halfling in Thundering Steppes for plates, utensils and cups.
Use a dimensional pocket expander to increase your housing item limit by 100 items.
Look for items that reduce rent payments (coin reduction). *One is a /claim item Treasure Hoard
The backs of certain Altars make great rock formations.
If you're moving object around your home and grab the wrong one, simply hit ESC and it will go back to the original position.
When looking to light up your room use lights that have a 'warm light' shining brighly from them. If it only gives off a 'gentle glow' it is purely decorational.
Layouts trouble? If that item just won't stay spun, flipped, or otherwise turned around for you, try adjusting the number by .1087 (for example), rather than an even 0.00.
World-wide Decorating Chat Channel! Simply /join antonia_bayle.homeshow (/join homeshow if you are on AB server) and chat with decorators across all servers. Sorry PvP players, this won't work for you.
Guild Hall Tips
Keep lag down in guild hall areas that people use a lot by reducing the number of items in those places. Save your high-count creations for areas that won't hold transportation or merchant hubs.
If your guild hall takes too long to load, try reducing the number of unique items it has. Use the same style bookcases throughout, or counters, or rugs..
Make it big! Most guild halls look best with items scaled to fit the hall. (Keep furniture, etc. useable though)
Be careful with Marketplace (Station Cash) items, most of these are not able to be place in guild halls.
