So this is not much of a guide. You have guides on InfiniteAion website/forum. This is only what i did and for me, aion now works perfectly.
So if you dont understand or have problems with connecting to their servers try this, maybe you get it at the end.
1. Download Aion Client from Here (Says [1.5.0.9])
2. Extract files using WinRaR
3. Launch NCSoft Updater
4. Change settings - Change to North America
5. Double Click Aion on the list, Updates will start > This may take a few minutes or hours... I would say 1h max but depends on the internet connection.
6. When it finishes updating close NCSoft Lanucher.
7. Download InfiniteAion Patch and put the files in your Aion Folder.
8. Get the Bin32 folder (from here - Password: infiniteaion | or from here - Password: iarules)
9. Once you replace the Bin32 from there, get the no_ip_restrict.rar (from here) and extract it to your bin32 folder.
10. Edit version.ini (inside your aion folder) to Version=1.5.1.5
11. Start the game.
If you dont have time for step 1. then do same as me from step 2. (if you already have some version of Aion downloaded/installed)! Let me know if you experience some problems!