Almost no work involved. We use nice bottles that have had other things in (vinegars etc.) and use olive oil. We sterilise the bottles in the oven and heat the oil before using it.
The herbs need to be dried stems (doesn't look very good if they're just bits and pieces) and just dropped into the bottles and kept for a week before being used. Rosemary is superb for this as it works so well for flavour and looks.
If you use fresh stems then the moisture in them can help to create mould and dangerous bacteria. The use of fresh would require you to acidify and heat treat everything.
If it's going to be used quickly it doesn't matter so much.
We tend to do three types of oils:- Rosemary, garlic and chilli (plus a combination of each) but others are OK as well.
I've just grabbed this off the net and you should read it.
http://umaine.edu/publications/4385e/