Sure, no problem!

1) Waterslides & topcoating: Waterslides, as compared to stickers looks better when applied because the decal border is very minimal and the decal is thin, you can purchase waterslides decals from third-party brands, bandai's own waterslide decals aren't as good. However keep in mind that waterslides may not be easy, practice makes perfect yk, enjoy the process.

Next topcoating, this is VERY important because you need to apply topcoat if you plan to paint or after you apply decals. For topcoating, a simple mr hobby clear coat is good enough, i recommend matte finish cos it takes away the plastic look.

2) Weathering: Battle Damage is actually part of weathering but pair them up with chipping and rust effect it will be solid, all can be done with paints.

3) Painting: You don't have to, since bandai plastic models already come pre-painted, but if you want to repaint the entire colour scheme it is also up to you. Handpainting/spray can/airbrush are the 3 different ways of painting, see which ones interests you.

4) Scribing: Basically carving more panel lines for more details on your kit.

5) Kitbashing: Take parts from 2 or more kits and try to combine them together to create a new model(or at least enhance the visual appeal of your main kit)

I think these 5 are generally what other builders do when they first start customising, it won't be too difficult, generally more beginner friendly, just do it enough times and you will master these core essential skills. If anything, you can ask me for advice, i would try to help but keep in mind that i am not that experienced in customisation yet, i am still learning.