Basically, you will need to find the name of the component. If it’s a circuit you’re building from someone else’s design, you should find the component’s name on the schematics. If you’re looking at a physical component, the name should be printed on the component itself.
Then, look up the component’s data sheet. Most (if not all) data sheets are available on the web. Just Google <your component> “data sheet”.
When looking at the data sheet, be careful not to confuse the “Absolute Maximum Ratings” with the “Electrical Characteristics”. The AMR, like the name suggests, are absolute maximum, above which the component is likely to be fried. Do not design according to these values as the working point. The EC give you the data you need for the design. In these you’ll find either Maximum or Minimum rating for each line, and sometimes an additional “Typical” rating. The rating given (Min/Max) is the worst case. You should design your circuit to work below these ratings.
BTW, some components are “generic” (resistors, capacitors, and the like). For these, you’ll need to recognize the component class. I don’t know of a way other than experience, or someone pointing these to you.