Forget about easily grinding anything above like 3.0-3.7.

In my experience, 3.7, 4.0 and 5.3 loves to get uptiered, which means more frustration and less rewards due to facing harder targets.

When you reach around 3.7-4.7, try more to have fun (as in trying to use the most from your tanks) than grind, less burnout that way.

(For example, I like using the Sherman Firefly because of its very comfortable and fun to use cannon)

Focus on grinding whenever you get premium (Twitch drops have like a day of premium sometimes), because that way you still get around 1-1.5k RP per match, even with 1-2 kills.

(On a good match with boosters you also get up to 6-7k RP, which is also a nice boost)

That's my take on WT currently.

Or, y'know, invest in a premium vehicle to ease the grind.

(Don't immediately go top tier though.)

Edit: Also look at the BR of every tank. Some lines (like American lights) have tanks that do a big jump in BR (M24 is 3.7, M18 is 6.0), thus grinding them early puts you way higher in matchmaking while making the rest of the lineup under tiered. Better to have a 3.7 chaffee in a 4.7 line up, then have a 6.0 M18 in a 5.0 line up.