One thing that would be good to know is whether you are wanting to shoot in a studio type environment or have a photojournalist approach with a need for mobility. The wildlife could be done from a blind or stand if you want to create studio quality shots or are you more of a hiker/camper coming across wildlife and taking shots when the opportunity presents itself. The portability requirement, if applicable, could have a huge impact on recommendations. There are some, such as Sean, who do carry studio type lighting to outdoor photo sessions and set it up on site as that is what is required to achieve the level of lighting control to meet their needs. Other people will carry a few flashes, improvise holders on site and are thoroughly pleased with the results.

The point I am trying to drive at is that there are many approaches to lighting and without knowing what your preferred approach will be it is not easy to recommend specific equipment. For someone starting out it can be overwhelming with so many choices. The other difficulty in starting out is not knowing through experience how to achieve the effect that you want. Just start using the equipment you have and spend time with ratios and angles to learn what you can do with what you have now.

You did say you are starting with flash units. Have you been using them? What method of triggering the slaves have you been using? Would cables or radio triggers improve your ability to work with them? In the shots you have taken, or will take in the near future, are you satisfied with the amount of light? Do you have the ability to control the transition from light to shadow to create the effects that you want? I know that I struggled with figuring out what to start with. Eventually it dawned on me that close examination of the photos and effects I was achieving and comparing to where I wanted to get to would be the best way to figure out what I would need to achieve it. That and a knowledgeable person behind the sales counter at the local camera shop who took the time to help me work through it all.