I find that caffeine, high fat foods, alcohol and honey (that's just me I think) do me no favors. Caffeine might give me a boost, but then I crash, so I end up drinking too much caffeine. I quit coffee and drink dandelion, ginger and red bush tea (dandelion and ginger I supposed to be good for us). High fat foods and junky foods (I eat organically so I probably feel this more than someone on a Standard American Diet (SAD) make me feel really tired not long after eating, and alcohol (even just 2 beers) gives me a three day "ugh" feeling like a hangover.
The library is a great place to start for lupus and diet books, eating lots of greens, (not as good as I could be at this), juicing is also great (it gave me a boost when I was in a mild flare).
Just try to eat as healthy as possible - think no chemicals (ie sweeteners, preservatives etc) and less processed.
Hope this makes sense (difficult to type with funky hands and lupus fog!)
There are many websites out there - but all have similar advice.