Camwoodstock pointed out that this Booru site is in need of a facelift, not just for UI but also for design. I have a short list of possible things that we could change (feel free to add or discuss items on the list)

-Actually showing titles (Possibly in a manner similar to DeviantArt)
-Tag aliasing
-Color coding tags?
-Automatic image resizing
-Folders? (could be helpful for separating by stream dates)
-Color scheme for entire website (just making the site look pretty in general)
-One image at a time scrolling (aka twitter, tumblr) vs multiple images at a time (deviantart)
-Expand on profile functions? Maybe bios?

Two good changes to help organize and prevent clutter, would first of all be to assign tags to categories like other boorus do, as explained in my thread "Tag categories".

Another important one that other boorus have to prevent duplicate tags, would be to have auto-complete suggestions in a dropdown list when you type in the search bar or in a post's edit box. This way, along with proper aliasing, if someone types a similar or incorrect tag it lets them select the proper tag from the list.

Another important thing to do is to get the tag wiki up and running. This way, tags can be given proper use descriptions.
Even better, this allows artists to have their own descriptions on their artist tags, letting them describe themselves and their work, and link to their own Twitter/DeviantArt/Pixiv/whatever.

Further more, we can set up systems for tags that imply each other.
For example, if someone uses the Robert Cop emote in a picture, the robert_cop_(emote) tag would imply robert_cop as the character .