Adjusting your road bike brakes is a pretty straightforward matter. And faulty braking, at any level, is something you don’t want.
First, you’ll want to look at what is going on. Maybe the brake pads aren’t the correct distance from the rim. In order to correct that, check to see if the caliper mounting bolt is screwed in tight. Then assess and make sure the tires are correctly placed in their dropouts and see how much, if at all, are they not centered in the caliper bridge.
Check your brake pads. If they are worn, replace them. To toe them in correctly, loosen the pad mount bolt and grip your brake lever to position them directly onto the rim. Make sure you clear both the tire and the spoke edge. If not, consistent braking will form a lip on the pad and if that is on the tire side, it will cause a blow out.
Look for the adjustment barrel and while gripping the brakes with your hand, turn the barrel counterclockwise to bring the pads closer to the rim or clockwise to move it outwards.
If your barrel has been turned all the way out or in, and you still need to do some more adjustments, you can bust out your allen wrench and fiddle around with the cable tension on the side of the caliper. Loosen the bolt that is holding the cable. Grip the caliper to where you want it, pull the cable tense and then tighten the bolt.