How to fix a faucet with little to no water pressure?

Is it well or city water? Was the water pressure always low? If city water, the supply is sometimes from a high water tank and the only fix is an in-line pump. Is there a bathtub or shower in the same room where the water pressure is okay? Are the pipes copper or galvanized steel? It may be that the pipes are clogged with scale. In which case replacement is the only fix. As for fixing it on your own, that all depends on your plumbing skills and tools.

Check the screen, it may be clogged up. Soak it in vinegar to get rid of the gunk, that may take care of it.

It maybe at the end of the run, so everywhere else gets priority. I don't think you can do anything about low water pressure, if it has always been that way. Had a thought - it might be that your pipes are internally clogged up because of hard water. they may need replacing or de-calcifying...........?

the spout of tap has a removal strainer at the end. It collects any debris from the water. Just unscrew and wash out the screen. Reinstall and taps should be ok

Make sure taps are wide open. Might have to install a booster pump along the run somewhere. Along with the above ideas.

It’s probably one of two things, first check the aerator to see if the screen inside is all plugged up. Happens a lot when the fire dept opens fire hydrants in the area or pieces of the washers breakup and clog it, the other suggestion is. The shut offs under the sink, sometimes as the faucets and washers age. When you have to use the shut offs for whatever reason. When you turn the water back on. The washers right there at the shut off either fall apart or come right off the end of shut off. Restricting the amount of water coming up to faucet. Easiest way to check for that is to turn water off in house or apt, make sure water is completely off, open faucets in bath and kitchen to make sure there’s no water coming out. Even flush the toilet. Get a pair of channel lock plyers and slowly and carefully unscrew one shutoff at a time. See if the washer is on the end. If not. It’s either stuck in the supply line going up to faucet or in pieces in the aerator. Again. Before you do anything. Unscrew the Arerator from the faucet spout. Clean the screens real good. If possible. Let me know how you make out. Thanks. Tom

Check inside spout to make sure there's no clog or regulator/restrictor.

Best wishes.........