Go into the settings.cfg (not the one in game) and find the line that says "CONIC_PATCH_DRAW_MODE". In the stock game, that is normally set to 3, but you want to change that to 0. Now, in the game, when you are in solar orbit encountering a planet, adjust your relative inclination so that it is aligned with your target. Then, target the camera to your target planet and you should see your trajectory around it. While you are still in solar orbit, you want to burn north or south to adjust it to get as close to equatorial as possible. You also want to make sure that the orbit is prograde (anticlockwise), not retrograde (clockwise). Then, you can do your small inclination adjustments once you are in a stable orbit. Alternatively, when you perform your retrograde burn/aerobrake, keep your apoapsis as high as possible after doing so, and if your ascending/descending node is in the right position, you can perform the inclination change at a high altitude, making the burn cost much less delta-v.