Testosterone is the safest steroid.
Potential problems from running Anavar: low HDL cholesterol, very low libido, low mental "drive" due to it not being very androgenic.
It doesn't cause lots of acne, water retention, isn't very toxic (but the liver toxicity potential is there) etc. That's why many say it's the "safest" steroid, but that's not entirely correct. Low HDL cholesterol isn't very safe for example.
The good: very nice strength gains relative to body weight.
You want safe? Low dose of test.