How do you code in Python ???

[Shagshag]

Hello,

Newbie to python, i was wondering how *skilled* guys code with it :

By now to write a function i write it in a text editor (with coloured
syntax), copy and paste it in idle try it, then go back to text
editor to debug it and so on until i've tuned it like i want, then
next function and so on until i complete module... And that's really
boring theses permanent back and forth...

So how do you do it ? Which tools do you use ?

(i'm on window, freeware if possible or not to expensive...)

Another one is which are "standard" coding in Python ? 

(thing like initCap, postfix private atribute with "_" and so on)

Thanks in advance,

S13.