The most important thing you have to remember is to move slow, not to rush through the levels, unless you want to get killed. In turn-based mode always look for a cover, and at the end of your turn if you have any APs left, go crounch or prone, so it's harder to hit you.

Some times it's good to have few APs left when ending a turn, 'cause there's always possibility that a new enemy comes to you way, if that happens you then may have possibility to interupt, act before him. You can then use all your left APs to find a cover or shoot the enemy.

Use realtime to do some maintenance activities like putting attachments on weapons or reloading weapons low on ammo. While the enemies don't mind watching you attach a silencer to a weapon, you'll be using action points that could otherwise be used in more damaging battle behaviors... like shooting.

Keep your mercs fairly close, It's always good idea to have some back-up, just remember while in real-time mode your other mercs could get across the sector in a matter of seconds, in turn-based it will take many turns, and they will never get there on time.

Remember to heal your mercs as soon as possible, cause most of mercs abilities, mainly APs are lowered because of the wounds. Also if the damage is bad, your merc will continue to lose health if not healed.

It's always good idea to carry a secondary firearm, if the primary happens to get jammed, brokes or runs out of ammo.

Always check out the weapon stats, and remember the damage and range are not the only fractions you need to check, remember the AP costs!

You need all the inventory space you can get, so when in real-time mode you can stock items like ammunication and half-used medkits together, to make up some room.