When I started building models I would just assemble them and neglect the panel lining. Now since I’m trying to make them look better I decided to panel line a few of them and see if they look better.
You could use a detailing marker or try a panel wash to detail your kits. The first method is rather straight forward its where you use a fine tip marker like a Gundam Marker to follow the panel lines on the kit. The second method involves diluting paint to a loose consistency and then using capillary action to make the paint flow through the grooves.
Once I’ve done that, I use acrylic paints to add finishing touches to make them look as close to the anime version as possible. Now the only thing remaining is a coat of flat top coat but since I dont have a can of that stuff I’ll do it at a later date.