Well... do you prefer a bit more modern strategy(ww2 etc), fantasy, medival n such or turn based strategy games?
For the first i recommend Company of heroes, a a great ww2 strategy game and Company of heroes 2 is coming out in like 2 months ^^
For fantasy i can recommend SC2, Sins of a solar empire(if you like spacewarfare n aliens)
medival and more historical i can recommend the Total war series, they are the most realistic and Epic strategys ever, for example Shogun 2 , Medival, Rome.
If you like turn based i can recommend Heroes of might and magic and Civ 5 ^^ enjoy