Starting with Hard-Surface Modeling
1. The Reference
The most important part of your 3D modeling is to have a good reference, if you are just starting out with Blender and modeling in general I would highly advise you to find blueprint images of the things you are making. I will use this Desert Eagle L5 Blueprint as an example to show how blueprints can help your workflow, since you can see everything you are making from three different directions, to gain more knowledge of the thickness of each part. I recommend you use the blueprints available on the-blueprints.com since they have a huge library of blueprints, from cars and ships to guns and missiles.
2. Starting shape
3. Adding Modifiers
This is the most important part of the tutorial, this is what makes your 3D model look smooth at the end, and what makes it look hard surfaced as well, it's very simple but makes massive changes. The first thing required to do is to select your starting shape which in my case is the cylinder and go to the Modifier Properties tab.
And trust me, no more than 4 is needed since, after 5 or more, you will reach around a few million vertices and the software will start bugging out.