If you've never taken var before, as with putting any new substance into your body (assuming you've already done due diligence to ensure that the substance itself is safe), start with a low dose & work up. Var is definitely the "safest" of the choices available as far as minimal sides, sustainable results and "most predictable". But because you are artificially altering the hormone content of your body, your body will react in it's own way. Start with maybe 5 mg for a few days. Move up to 10 and up to 15 if needed. If you are not on a tight contest prep schedule, there's no point to loading heavy doses and you have the time to run a longer cycle and experiment. Because you are looking at working with var, the types of sides you could expect would be oily skin / acne initially. That should probably give you an indication of a good dosage to stick with. Unless you don't mind the zits.
What brand of var were you planning on using? When discussing dosages, you want to make sure you know what dosage each pill or unit is and if it really contains that amount. For example, in testing certain brands (we tested them on EF), we found that some brands were consistent with what they said, some were underdosed & some were overdosed. And some weren't even what the bottle said they were.