Mars is never ever going to appear as big as a full Moon, but if you want to see it at the moment, it (and Venus & Saturn) will be just above the horizon from 2130 until 2230 tonight if you look due West. Mercury will be a bit to the right of Venus, but below the Horizon.
Venus is much brighter though, so you might have difficulty spotting Mars or Saturn. Especially as there will still be a bit of sunlight about. By 2300, all three planets will be beneath the horizon.
I don't know how often Venus, Mars, and Saturn are so close together, but that's the only thing which is remarkable about the positions of the Planets at the moment.
The best time to see Mars was earlier in the year when it was still above the horizon during the hours of complete darkness. That said, it's still very small, not very bright, and very far away. You're not going to see much more than a small red/brown dot unless you're using a very powerful telescope.
(
www.stellarium.org)
So keep an eye on the low Western sky between 2100 & 2200 for the next couple of weeks. You'll see one very bright object (Venus) and two not-as-bright objects (Mars on the left, Saturn on the right) converge to form a triangle on the 10th of August.
