Use turbo every chance you get
Turbo is a great way to get ahead of your competition. You can use your boost multiple times in a race so there's no major limit. This especially comes in handy when you fall behind by a bit. Using the turbo will push you up and you should be able to pass the next person ahead.
My only suggestion would be to be careful using it on turns. We wouldn't want to see you crash into the wall because of bad turbo timing. So, yes, although it's good to use it as often as you can, just still be a tad bit mindful of things like turns and obstacles. If you can maneuver those things while using turbo, then awesome, you're a legend.
Don't rely on drifting too much
Drifting does play a pretty important role in the game. On most tracks, they will tell you when to drift on a certain turn. You could, and sometimes maybe you should because they can help, and they look cool. However, you do not need to do this on every single turn.
Just steering like normal can get you through many turns, especially when starting out. And by drifting too much, it may slow you down a tad, allowing the closest person behind you to pass you up. So just bear that in mind before drifting. You may just need a little turn and you'll be good.
Use power-ups when possible
Arcade Mode in Kartrider Rush+ will really take you back in time to the classic Mario Kart games because it features several specialty items you can grab. Use these items to give you an edge on the track. I will say that Arcade Mode isn't for the faint of heart early on.
Some of the tracks are a bit tougher, and other players will use power-ups at will. This is why I'm about to tell you to do the same. If you have an item, use it. You can have two of them at a time. These can range from banana peels to heat-seeking missiles. Heck, there's even a magnet one that brings you closer to the nearest competitor.
Whatever you find, just make sure you use it soon, because if you don't then others will get you first. Now, things like the missile only work best if you're closer to other players. Don't use it if you're in first place, obviously. But something like the banana peel can be used if you're leading. In short, take advantage of all of the weapons at your disposal just like the good old days.
Play the story mode
Checking out the Story Mode in Kartrider Rush+ is a great way to practice against CPU drivers. Plus, you get a cute little tale to boot so there's that also. But the early levels have some really easy tracks to race on which is why it's good for practice.
You can freely play any race at any time. Now, there's a training section in the game that you can play whenever you want. However, if you want a freer experience without worrying about popup tips, then early story mode races work out nicely.
On top of this, you'll get rewarded too. You can earn currencies that will allow you to upgrade your kart or make purchases in the shop. You can earn some other forms of currency that will let you make trades in the shop. So you get a story, some experience, and good rewards for playing in the Story Mode. What's not to like, right?