First you need to realize it's an extremely grindy game. You would have to put in at least 1h a day to progress somewhat decently. More hours = more progress. So keep that in mind! If you're not up to that, you might consider not playing the game at all.

Secondly, although the game is over 5 years old and you've missed dozens of events, there are ways to get cars from past events. It will often take quite some time to get the really good cars, but it's possible to build a decent garage in 1-2 years (depending on the time and €/$ you spend).

Thirdly: as a new player it's best to focus on a few things first:

1. Focus for now on the cars you can get easily. The majority of the cars are hard to get and often have an opportunity 1x per year or so. Don't think about getting those cars unless there's a reasonable opportunity. Best is just to focus on the cars within reach, even when you think they're stupid and even when they're really terrible statwise (e.g. the Challenger SRT8 and Z4 are terrible cars to drive in the game, but you need them for now).
   
   
2. Career: play as far as you can. You will get stuck several times, but it's important to make progress here because it helps you in the rest of the game.
   
   
3. Daily events: be sure to do all the daily stuff, because it's needed to progress. At first you will get crappy cars, but you need those in the beginning.
   
   • Car Hunts are ideal to get cars AND to grind. Although I have most cars from hunts maxed out, I keep grinding for credits, import parts and trade coins.
   
   
4. Special Events (Seasonal): it will be hard to do something of value here as a newbie, but still try to grab the (few) things you can. Every bit helps. And event veterans often don't get past halfway without spending real money.
   
   • Mind also there's a starter event for the 488 GTB, be sure to do it, because it's really useful for a newbie!!!
5. MP: you need a few decent cars to get anywhere. The most important car to begin with is the DS E-Tense. It might not look good, but it's the best easy to get D class car for beginners and even veterans keep using it. Make sure to max it out as soon as possible. For C the Viper ACR or Pininfarina H2 are best easy to get MP cars and in B the Corvette Grand Sport (GS for short) is a must have.
   
   • Reason these cars are so good is because they have good handling/nitro, which makes them easy to drive. This is much more important than a high top speed. Also rank say not a lot. Check out my FAQ to learn more about this: https://www.reddit.com/r/Asphalt9/wiki/guide/part2/#wiki_what_do_rank.2C_top_speed.2C_acceleration.2C_handling_and_nitro_mean.3F
   
   
6. There are some new features that can help you out:
   
   • Auto-claim: at garage level 12, you can auto-claim some daily events (daily car loot, cup and credits heist). So getting to GL12 is a must for easier grinding!
     
     
   • Starway: there are 4 recurring Starways, every 3 months. For a newbie not an option YET, but later on you will get some good cars from it.
     
     
   • Showroom: this update introduced, it gives several decent cars. It's a HUGE grind, but might be worth it. For you the Elise event is a must do, because it's even better than the DS E-Tense (maxed out).
   
   
7. Spending:
   
   • Credits: only upgrade cars as far as needed. In career you often don't need maxed out cars. Just upgrade to the recommended rank. Only cars like the DS are worth it to max out.
     
     
   • Tokens: best is just to save them for now. Start thinking about spending when you have at least 10-20k. Ask here for advice if you think you need to spend.
     
     
   • Season tokens: this is a new feature, for now I think saving them up to max 66/33k (with LP) is best and convert to 2k. Ask here for advice if you think you need to spend.
     
     
   • Real Money: the game is playable F2P, but progress will go slower obviously. Most offers are way overpriced, you can spend €100 without even getting a car. The best (or least) worst offers are the Legend Pass (LP) and Daily Events Pass (ONLY for good car hunts!!! Ask for advice again here when in doubt!)

Be sure to check out this subreddit's wiki, it has many good stuff. Sreglov wrote this guide on reddit and the FAQ with mod erik_g but there are some great guides as well (this, this and this).

I just repost and edit that on steam.
There is original: https://www.reddit.com/r/Asphalt9/comments/17f7ojf/new_player/