how toproceed stepwise to compare acidity and basicity of different substituted aromatic compounds.please illustrate with some examples

In order to look for acidity and basicity in aromatic compounds, always look for the factor which are contributing towards acidic or basic strength.
Acidic strength-I effect-R effect
Basic strength+I effect +R effect

The acidic strength order is:-

Here we can apply the above rule
I is most acidic due to high -I and -R effect of NO₂
II is having -I,+R (Cl) group where -I dominates.
III is having +R,+I (CH3) group where +R occurs through hyperconjugation instead of resonance
IV is having +R,+I (OCH3) group
We have to check the strength of the effects and how they can be useful to determine the acidic/basic strength.