Weeds do not like competition. If your lawn is happy, weeds have a hard time surviving.
The same applies to flower beds and gardens. Timely maintenance makes a difference.
the Internet is a great place to research your pest. It is easiest to search in Google images.
Once you have identified the culprit, there are organic solutions for control as well as chemicals when appropriate.
This is a collection of photographs that I have taken over the years from my garden. It is a small sampling.