This will be the best option for you;
- Install clockworkmod recovery by following the details on the first post- Easy process, shouldn't run into any problems. If you run into the most common problem which is about drivers then follow this link and it should fix it for you; http://sanfranciscoa...n-francisco-ii/
. (Only follow that one page, you can close it after you've finished installing the drivers as you don't need any more information from there).
Then you can flash an Orange debranded ROM or Fish N Chips. Fish N Chips is a custom rom which runs better than the Orange ROM, it looks better, has notification toggles etc and everything works on it. If you don't want to touch a custom rom then just go for the Orange Debranded but I'd recommend Fish N Chips.
Orange Debranded; http://www.modaco.co...ty-gingerbread/
Fish N Chips: http://www.modaco.co...5-testing-rls8/
Before you flash a new rom you should boot into the new recovery you've installed (Turn device off then hold down power on button and volume down) and go to backup/restore and do a backup. Just in case anything goes wrong.
Almost done. Now you should partition your SD card, if you can tell me what gb it is I can try and help you find a suitable option for the partition. Before you partition your SD remember to back it up by transferring all the files on your SD onto your computer as it will be wiped during the partition process.
You partition it by booting into Clockworkmod Recovery and go to advanced then select partition sd card, you'll get some options now; "Select the EXT size that you want (128M, 256M, 512M, 1024M, 2048M or 4096M)" (I have a 16gb sd card so I did a 1gb partition and that's fine for me but you should do this based on the size of your SD, the second menu will ask you to set a swap size, i think I chose the 2nd one from the top (The one after 0). I'd wait for someone with more experience on partitioning to comment before you do this.
After you partition it you can flash the A2SD scripts; http://www.mediafire...e69w1wxegx5ak4f
Then you boot the phone, go to the market and download https://play.google....o.a2sdGUI&hl=en
(A2SDGUI) then open it and accept it when it asks for root permission, click the 'Dalvik' menu and then click 'Dalvik cache on sd ext' then click 'move and rebuild', your phone will reboot and then you'll have plenty of space for apps. I had over 250 apps installed on previous ROMs with plenty of space left for more.
You 'flash' things via Clockworkmod by putting the files onto your phones SD card then booting into Clockworkmod Recovery (power button and volume down) then doing a full wipe (Wipe data/factory reset, wipe cache and then advanced wipe dalvik cache and battery stats). Before you do this do a backup though, always do a backup! Then go to 'install zip from sd card' then 'choose zip from sd card' and find the file you wish to flash then select it and when it finishes click reboot phone and you're done.
I hope I've helped, and I apologise for the huge post. I wasn't sure if you were experienced or not when it comes to Android development so I tried to keep things simple, if you're experienced then this will just be a doddle to you.