Ubuntu recommends that EFI boot partition should be 200 MB and Windows 8 create EFI partition only of 100 MB. So first I installed Windows 8 and then Ubuntu. Windows 8 create only 100 MB EFI partition so I stopped the installation of Windows 8 in the middle and used Live Ubuntu from pen drive to boot and open GParted. Deleted every partition except sda1 and sda2. Now change the size of EFI partition to 400 MB.
If for some reason GParted fails than use Ubuntu installer to resize the EFI partition. When using Ubuntu installer do not delete sda1(Windows recovery) and create EFI partition of 200 MB and continue with installation and cancel Ubuntu installation after disk formatting stage has done. Now go to Windows 8 partition. Delete every partition except sda1 and sad2. Format(not delete) the sda1 and sda2 with Windows 8 to clear any old entries for fresh install and creat 100 GB partition using Windows 8 partitioning system. Windows 8 will automatically create sda3 and sda4. Windows create sda3 - 128 MiB partition automatically while installation. Windows 8 will install successfully. Now with UEFI only Windows 8 boot by default.
HP Pavilion g6-2313AX has secure boot and I have disabled the legacy support from BIOS to avaoid any future problem while dual booting Windows 8 and Ubuntu 12.10. For it I used the GParted for partitioning the 1 TB hard disk drive.
The last I heard, WUBI didn't work well on UEFI installations; however, I don't follow WUBI very closely, so that may not be accurate. If it is accurate, your best bet is to ignore any WUBI-style boot options and instead boot the Ubuntu CD/DVD directly using the firmware's boot manager (usually accessed by hitting a function key soon after you power on). You may see two CD/DVD device entries in the list; be sure to select the one that's marked as being for "EFI" or "UEFI" and not one that's marked as "BIOS" or "Legacy." Once the installer is booted, I recommend dropping to a shell and checking for the presence of a directory called /sys/firmware/efi. If it's present, you've booted into EFI mode; if not, you've probably accidentally booted into BIOS/legacy mode. Do not proceed with installation in BIOS/legacy mode. Although you can get it to work this way, you'll need to jump through some extra hoops, so it's better to go back and at least try to get the installer started in EFI mode.
Ubuntu 12.10 does support Secure Boot, but this is a brand-new feature and so it may yet be buggy on some systems. If you want to eliminate Secure Boot as a possible source of trouble, you can certainly disable it using your firmware setup utility, but the details of how to do so vary from one system to another.
FWIW, part of the problem with UEFI systems right now is that, despite a strict and detailed UEFI standard, manufacturers are introducing their own unique bugs, quirks, and idiosyncratic ways of doing things. It's like a cross between the Wild West and the Soviet Union. The point of this is: If you get a computer and it's giving you too much grief getting the Ubuntu installer to boot, return it, and make it very clear why you've done so. You might end up with something a little less mind-bendingly dysfunctional. FWIW, I've seen more problem reports about Sony and HP machines than most others, but I don't know if that's because they're worse than others or because they're more popular than others.