new player that needs help

im a new player who has watched alot of starcraft 2 and such. im trying to increase my skill before i enter ladder, so im playing campaign, even though im aware that its not the same. what im wondering is what race would best fit what my play style is. im a ranged fanatic. i love sniping in fps, and any ranged play. i thought that playing a muta harras build looks cool, but then i also like the look at a defensive tank play. any other suggestions?