Integrating bespoke code and considering upgrades?

Hi People

I'm pretty new to nopCommerce. The system looks great and I can't wait to get going and start using it.

I was hoping for a little guidance. I can see myself making small bespoke tweaks to the source code. When new versions come out - obviously I would like to upgrade to the latest version to take advantage of the new features.

Is there a common way changes should be made to the source to simplify upgrades, or do you need to manually re-integrate your changes again after the upgrade?

I was after a way of overriding code safety and cleanly.

Thanks for you time.

I have just stumbled across this article that may help me along a little - https://www.nopcommerce.com/boards/t/11315/how-to-extending-nopcommerce-v20.aspx

If anyone else has any other input on this please say, I'd love to here it.