These days, most cars comes with adjustable turnbuckles. As many as 7 turnbuckles in 1 car. 4 as the upper suspension arms, 2 for left and right steering rods and 1 on the steering servo. Since most turnbuckles (in RTR or Kit)come really tight, so when you adjust the turnbuckle, it will pop out from the ball joint (Popping the ball joint in and out often is bad - once the plastic ball cap is too loose, it will pop out under the softest bang of your car).
Best is when the plastic ball caps must screw into the turnbuckle smoothly (but not so loose until the turnbuckle can move under vibration). The best way to do this - screw the turnbuckle into the plastic ball cap all the way in (tip - not so deep until the ball cap end) then unscrew it. Remove any plastic debris from the inside of the plastic ball cap with a needle. Then re-screw in the turnbuckle, you will find that it screws in much smoother than the first time, right? If it is still not smooth and still feels very tight - repeat this step again. (tip - do NOT mix up the ball caps - one side is normal CW going in and the other side is Anti-CW going in). Tip - mark those ball end that is Anti-CW with a marker pen. Mark the Anti-CW side of the turnbuckle too, so you will never mix them up.
Other tips - if the first time screwing in is very tight - do NOT use a pliers on the plastic ball cap. Wear a pair of thick glove (leather is best), this will not damage the plastic and your hands won't hurt. OR drill the hole - use about 0.5mm smaller drill bit. Eg, if the turnbuckle is 3mm then use a 2.6mm drill bit. Do NOT put grease in the hole.
Do this well and you will be able to adjust toe-in or toe-out easily and quickly anytime. More toe-out means more steering. This is important as it affects how your car steers. Adjusting chamber requires more understanding. Start with trying to get the tires flat (maximum contacts of the tire and the ground) on the ground with your car fully loaded. I will discuss more on chamber in another topic.