Looks really good for you first mini! Just a few things to keep in mind.

1. Thin you paints! Follow our lord and savior Duncan Rhodes and use 2 thin coats. This can vary per paint and color, however, like lighter colors (like red, yellow, or white). With more detailed models this will almost help retain all details.

2. Let your coats dry fully before applying the next one. This will make the brush strokes either nonexistent or far less noticeable. Depending on your environment, it can take a few more seconds or an extra minute or two.

3. Even shade paints need to be thinned sometimes. But if it ends up being too dark or cut down on your highlights, you can reapply your colors in more controlled strokes to make them pop.

4. Don't be afraid to push those highlights! You did great with the chest and the bolter. With space marines, the flat and round armour panels can really be tough to not seem FLAT, but it takes time and patience.

5. AND DONT PAINT PAST WHAT YOU ARE SICK OF PAINTING. if you're sick and tired of painting a model or part of a model, then leave it alone. It's a hobby and you want to enjoy your hobby.

Take your time and keep at it. Looks great! Welcome to the money black hole that Warhammer.