I terms of putting things together the guild masters in the original rule book are as easy as it comes to put together although if you have a bit of patience most other sets aren't to bad (except Ramos' set, they're a pain in the arse!).
I wouldn't worry too much about the painting, you aren't going to be decent straight away, my early models loked like they were painted by a 5 year old on a rollercoaster.
As you get better you can always just strip your earlier stuff and repaint them. There's plenty of guides online, best thing to do is read a guide and just have a go. It doesn't matter what the final product looks like, as long as you enjoy have a go.