What are the best settings for an indoor shoot for my Nikon D3000?

I'm new to photography. My passion shows through my photos but most of the time, I'm simply just messing with the settings until I get what I want. I prefer to do photography in natural light and really wasn't up for an indoor shoot. It is an existing client so I couldn't say no. Here is the equipment that I'm working with: Body- Nikon D300
Lens- Tamron 28-300mm telephoto
Lens- Nikkor 70-300mm telephoto
Lens- Nikkor 18-55 stock lens
Flash- Nikon SB-600 Speedlight

I will be taking group photos and individual photos of a jazz band in a studio. I will only be using the equipment listed above. What do you suggest for group as well as individual and head shots. I would like a warm light.

There are no best settings for any shooting situation because each is unique. You'll have to take a few shots, look at them and adjust from there, that's all you can do unless you have a stand alone light meter.

It all depends on a lot of things. Your first concern is lighting. The safest, if you don't know what to do is to use flash. I see you have a very capable flash with you. Second concern is distance. If you are allowed to stay close, the 18-55mm will do wonders. If not, use one of the longer zooms.

As a side note, since you already have an 18-55mm and a 70-300mm, I see no use for the 28-300mm except for when you are too lazy to bring the other two. It's redundant with 28-300mm already inside the 18-300mm range of the other two lenses.

If you still don't know how to set-up the flash, check the manuals and if possible use Auto on everything. Too many details to explain for such a little text box. You'll have to learn photography more.

Jim is correct. Without being there to see the studio and lighting, it is almost impossible to guess the camera settings. Shooting all manual with raw images is the best way to go, BUT… You need experience to have an idea as to where to start with settings.

You want to use the lowest ISO you can, BUT that will be dependent on the available light and your camera. As far as the aperture… That will be dependent on the DOF you need and (again) the lighting.

Most experienced photographers can walk into a session, look around and have an idea of what ISO/aperture/shutter speed they will need and then adjust appropriately.

I always stress that people get a camera they can use instinctively for a reason. I did a shoot last week and was told "this is the lighting you will have", so I set up for that. Unfortunately, what the director said and what the lighting director gave me when everyone was in place was two different things. It took about 10 seconds to readjust and meter it, and life was good again.