After time your sink faucet can become clogged with debris that comes through your pipes. It can cause water to spray out all over the place or drop the water flow down to just a trickle. Its good to clean your aerator out from time to time and check if your washers need replacing.
First try unscrewing the aerator by hand. If you can’t remove it use pliers with tape covering the teeth so not to damage the faucet. After removing the aerator, disassemble it and lay the parts out in order to help during reassembly. Inspect the washers and if they look cracked you should replace them now. Place all the part except for the washers in white vinegar for about an hour then gently scrub away the buildup with a soft brush.
Before you reassemble make sure to run the water to flush out any loose sediment. Reassemble the aerator and screw the assembly back onto the spout. Make sure to gently snug the aerator tight with your pliers.