The reason why kitchen sinks always clog is because we don't mind what we are throwing down the drain. Instead of throwing it to the bin, we leave it on the drains, ranging from excess meat/vegetables to kitchen oils. Surely, it will cause a buildup along the pipes under the sink. It is also important to note that grease and coffee grounds will cause a clog down the pipes.
Now, whe your sink is clogged, we can try using some materials that we can easily get a hand on.
You can use a plunger. Cover the drain opening completely and plunge 6-10 times vigorously.
You can also use baking soda and salt, mix them together (1 cup baking sode and 1/2 cup salt). Pour them down the drain. Let them sit for a few hours or overnight. Pour 2 cups of boiling water down the drain.
You can also use baking sode and vinegar. Pour 1/2 cup baking soda with 1/2 cup of white vinegar. Pour hot water thereafter. This should be repeated several times until clogging is gone.
You can also use and unbend a wire hanger to try to push down the clog or ever remove the clog, whichever works for you.
Lastly, you can call a plumber to fix the clog.
Bottom line here is to always treat your kitchen sink with respect. If we care for it in the present, surely we will not need have some problems to deal with in the future.