Hi, Beth,
If you want to get into oil painting, I would recommend you identify which colour palette of a particular artist that you like (it can either be from an old master or any other artist) and learn from that colour palette. It is also a good idea to learn painting from a limited palette. From the colour palette, I would make up colour charts, with 5 values, one in pure colour (and mix with white for value gradation). Then for each of the colours, make up a chart with that colour mixed with each of the other colours in the palette. This is also done in 5 values. It is a good exercise to learn about the colours that you have chosen, how colours are mixed to get a certain colour, colour harmony, etc. It sounds tedious and time-consuming, but you will be amazed with what you will learn from it.
This will save you a lot of money buying a lot of unnecessary paints, because you can mix any colours that you like. It also helps you to understand how colours behave better in painting.
I used to paint in oils, but switched to pastels because it is relatively easier with all the cleaning up, etc. I am now getting back to oil painting. Hopefully, I will find some good ideas for some new oil paintings!
Mai