UEFI

1. Download Windows Technical Preview - Link
   
2. Create bootable Windows USB - Popular solution it seems is Winusb, however it didn't work for me. I used less well known Yumi. I tried both, however Dell's BIOS didn't recognize a bootable USB created using Winusb. Yumi does the trick
   
3. Reboot from USB and install.
   
4. Well almost. Windows 10 needs UEFI to install, and my Dell laptop shipped with an relatively old BIOS version A04 which did not support UEFI. Dell added UEFI capabilities in BIOS version A07/08 onwards. However, DELL doesn't give BIOS updates which can be installed from Linux. They provide Windows32 EXE's only. I was stuck for a long time in trying to update BIOS with Ubuntu. Thankfully, this is a known issue, and there are steps published to work around it.
   
   The one which worked for me was use FreeDOS bootable USB stick to update Dell BIOS. Thus I created a FreeDOS bootable USB, booted from it, and installed Dell's latest A018 BIOS (Steps using Unetbootin).
   
5. Updated BIOS will now give an option to boot UEFI, but only via Network. Not via USB. I was stuck again. After much prodding I observed an odd option in UEFI menu, which allows one to add your own UEFI boot method. It will list devices from which it will allow UEFI boot, and your Thumb Drive or DVD should appear as a listed option automatically. Follow this link on Dell's website to add UEFI boot option
   
6. Viola. Boot using the newly added option, and you can install Windows 10 now.