There's a bit of controversy regarding Sav's requirements, but I'll tell you what I do. I've been keeping/breeding various monitor species for about 30 years now, and I still learn things about husbandry- so stay open to various opinions!
Sav's need daytime temps in a gradient from around 85-100 degrees. Nighttime temps down to 70-80. Undertank heaters work well for this.
I believe a basking light is essential, as well as a UVB light (this often starts arguments, but I can only point to the health of my lizards) Basking area should be around 120 deg Fahrenheit.
For younger monitors, I use 30-40 g tanks, with astroturf as a substrate, with a box at one end full of clean dirt- keep the dirt (actually, decomposed granite works well) damp, which will keep the humidity up, and allow the monitor to burrow. The dirt should be at least 3/4 as deep as the monitor is long. A water dish that he can fit his entire length in is important, filled just high enough to cover his back when he lays in it. Change the water daily, as he will most likely defecate in it.
For a diet, I get them on mice as soon as possible, and feed crickets as long as they'll continue to take them- mostly for excersize. Sometimes once a monitor begins eating mice, he will stop taking invertebrates, however.
Most monitors are bottomless pits- in my experience, you can feed mice as often as you like (at least two, twice each week) until he reaches maturity, but alternate foods like dogfood or hamburger should be avoided unless you have a recovering lizard who needs to bulk up- and even then, feed only in moderation. Excessive fatty foods can not only make your monitor obese, but lead to liver disease.
Hope this helps!
Jamie
and I want to go on the right way to keep it healthy 