to improve tactics and strategyYou should not put tactics and strategy words in the same sentence, these are very different things.
There are 3 levels of detail:
- tactical (which unit shot at whom and when)
- operational (moving around groups of units)
- strategic (mostly economy, decision what kind of units to build, generally supporting your war machine)
RTS do not have tactics It's operational + a bit of strategy. If you want tactics, it's in hex map turn based wargames (Panzer General), note that these basicly never have any strategy involved. If you want strategy, it's best portrayed by the so called grand strategy games (simulations of whole nations).
Note that a combination like tactical + strategic is extremely rare (it basicly does not work, the only exception I can think of is Civ5). Generally, in one game you can have only levels that are near each other (like tactical+operational or operational+strategic), tactical+strategic is too far away.
Or to put it shorter, you can't at the same time simulate a whole nation's army (10 million soldiers) and order which one of these individual soldiers shoots at whom