Hello Melo
It's really up to you; however, I must say that I am with you regarding to getting the overall shape of the part builted first, and then push vertices around for the finer details.
Before to begin, I recommend that you prepare the overall shapes first and be happy with it. In this case, perhaps will be something similar of what
you are looking for. I took those polygons and detached them as a clone. The reason for me to doing so, is to have the originial topology and shape
intact just in case I don't like the result. As you will see in a few moments, I will delete this polygons and attached the desired result to the fuselage,
weld some vertices and make the shape as one again.
View attachment 36304
Then, I performed a boolean operation to take care of the necesary topology to conform the landing light hole. Those polygons were the base to
achieve this:
View attachment 36305
Once I am satisfied, I deleted the four original polygons and attached this shape to the main fuselage. This part depends on the result you are
looking for. To be more clear, I could have the original fuselage intact and leave this part as a separate element. This is the perfect example on
how many designers built all posible variants in their models. Once you have the general parts made, you can desing all those lovely details and
make the desicion if you want to build several different models OR... you might want to design a gauge with conditional display options, where
the happy final user may decide which items need to be shown when she/he fly the aircraft. It is really up to you! Ok, lets continue with this.
In my case, I attached it to the fuselage to obtain one single object. This is not the case for the next part! Again, I took several polygons and detached them as a clone. And as you mentioned before, I extruded polygons and pushed some vertices to get what I wanted.
View attachment 36307
I will show you another image where you can see more details:
View attachment 36309
From this, I get the final result as a separate part or element if you want:
View attachment 36310
Now, we have the fuselage and this part as two different entities!
View attachment 36311
That was my take on how to build this things! I really hope that this make sense to you as well.
Happy modeling my friend
All the best,
Sergio.