Between Rivals, Draft and Squad Battles I've played over 142 games and made 162,000 in match coins (ranked 156th in my region) on FC 27 and here are my tips (LONG POST).
1. Don't get frustry (frustrated), this game is HARD but it's rewarding when things finally start to click.
2. Don't quit! You can get up to 850 SP a day just playing the game. I think I'm averaging around 40-60 SP per game in rivals and the coin boosts this year are significant so it's absolutely worth staying in a game especially early on to collect those things.
3. RB dribbling (especially with someone that has tech or tech+) is a great way to move around and get your opps players out of position. Sometimes I'll just initiate RB dribbling and streak across the pitch to see if that opens up something on the other side. Very good on the wings and also cutting up the middle with Musiala.
4. If you think you see someone open for a pass you need to double, triple check that they are in fact open because lazy passing will punish you this year. Spamming pinged passes does NOT work this year.
5. Shoot near post: it might actually be broken but it works like 99% of the time and GKs just don't have the animations to save it.
6. Prioritize First Owner in the gallery: the 500% boost you get for 10x first owner items is massive and gets you way more gallery points so you can get that level 10 Holo Hero PP quicker.
7. When you open a tradeable pack, flick the right analog to the left a few times until you can see the player prices. A random "nothing pack" with players below 82 might have some players going for crazy prices because of the gallery and that's the easiest way to find out the price.
8. Speaking of the Gallery, get a notebook and write notes in it to help you with your progress. You can also draw in it to help you manage the stress of the game. I like drawing sheep and chickens.
9. Have a nice little beverage next to you when you play so you can sip on something to refresh. I like water or an iced coffee.
10. Don't stress. Play with passion and have fun!