some ideas, feedback etc:
the client
exp/h information, I couldn't see this anywhere on the beta and maybe you could display it in a way similiar to how zezenia does it:
it's better than hovering over your experience bar (like real tibia) but that works fine too if it's too much work to change.
you could also add buff bars, for example in that zezenia screenshot the blue bar on the top right shows how much haste time you've got left.
maybe add manabars? I really like that feature in medivia online which is also a server based on otclient (should only display your own mana bar, not other players)
you should also change the default button to disable "chat mode" from enter to something else, since you often press enter when dragging gold and doin other stuffs which causes causes chat mode to activate again. maybe you could toggle it on and off with ctrl+enter or ctrl+j (in zezenia it's ctrl+f) or some other buttons. so that you can actually use wasd walking without much problems.
add mapmarks in cities for basic shops, like distance npc, pot npc, bank etc. It was frustrating in the start running around in big cities looking for those and I could definitely see new players getting annoyed by that.
I also thnk that the exprate should be somewhat lower and that stamina shoud be enabled but it could regen abit quicker than on real tibia.