Could someone provide me a general strategy for all maps when it comes to your starting troops? For the most part, I normally start with this roster:
 
- 2 scouts
- 1 engineer
- 1 Lancer
- 1 Sniper
- 3 Shocktroopers
 
For the shocktroopers, I always assign one as backup for each scout and sniper. 
 
I'm not trying for Rank A runs or anything. I just need a good strategy that will prevent anyone of my soldiers from getting killed.

That's similar to my basic roster. However what units to use and where to place them depends entirely on the map you are fighting on and just boils down to trial and error. Generally speaking I use people that like each other and pair them together for bonuses, stay behind cover, and take the high ground whenever possible. Also, I always kept an engineer with my tank since if that blows up it's game over.

Generally you will take more scouts and shocktroopers than any other unit. Specifically which troops you should take though is going to depend on the map. A few more tips:

• Always take Rosie, Alicia, and Largo since you'll get an extra command point for each of them.
• Don't take more than one engineer, and always keep it close to the Edelweiss (it might be appropriate to take two on some of the later maps, but early on stick with just one)
  
• Keep your units behind cover. Also, don't forget that you can pretty effectively use your tank as cover for your other units.
  
• Try to choose units that will perform well in the map's particular environment (desert, forest, city, etc.). Also attempt to choose units that like each other and keep them grouped together in combat.
• On maps with multiple command points, it can often be easier and quicker to make slower units like snipers and lancers retreat at the base closest to them and then call them in as  reinforcement at the forward base.
• Don't forget to research advanced equipment. Also, make sure that your troops always have the best equipment available. In general, I would say don't bother using the enemy equipment that you obtain since it tends to be too inaccurate, but definitely use all of the royal equipment that you're rewarded with later in the game.
• Don't be drops some troops to try out new recruits. Some troops are definitely better than others and unless you experiment some you might completely miss them.
• Do plenty of skirmish battles to level up your troops.
  

Thank you for the very useful replies. I'll keep those helpful hints in mind. I've since stopped using shocktroopers for offense because their APs are just too limited and I find them to be better at pinning down bottlenecks.
 
@Chaser324 said:

"Don't take more than one engineer, and always keep it close to the Edelweiss (it might be appropriate to take two on some of the later maps, but early on stick with just one)"