New to Windows Mobile – HOW TO, DO’s & DONT’s??

Having bought a DELL Axim X30 4 years ago and never got down using it, I decided to give it a go – although it’s loaded with Windows Mobile 2003 SE – and due for an upgrade. But my question is how do I start out on this – I have no clue of how the mobile platform works – how do I upgrade to Windows Mobile 5 or 6. Pretty much clued up on WinXP here – and see myself as an advanced WinXP user. But the mobile world still a mystery. Anybody have any tips and answers on my questions?