I was like you at first.

For combat, the trick to staying alive is to be very careful and patient in combat. Always move in the blue regions and set up for overwatch. The big problem with the aliens is when you spot them they will get an extra scatter move which fucks you up since they have a good way to flank you. When you spot one group of aliens(usually they will be in groups of 3) kill them all before moving on.

I also recommend to try and promote one guy fast so you can unlock squad upgrades. Again be very careful with your high ranked soldiers because losing them can really screw up your game. Once you have the squad upgrades you might want to focus lower ranked soldiers to balance things out.

For the getting money, prioritise on building satellites. Satillites give you funding but remember that there is a build limit so you need to make sure you construct satellite links/nexus. When you build your satellite links place them together so you get bonus increase to you satellite maximum.

Also choosing Africa as your base continent will give you a 30% increase in funding that will help out a bit.

If you're ever in a bind for money you can visit the grey markets and sell stuff there but it usually doesn't give that much.

When you by equipment upgrades by them by the squad not the soldier. For example, if you use only one sniper in squad only build one laser sniper and switch it out for which ever sniper you are currently using. This will save you money in the long run.

Final note, sometimes you will get really unlucky and lose some of your best soldiers. That will fucking suck so get ready for the emotional trauma.

TL;DR: Take your time and launch satellites.