Concerning resizing - even if the C4D quality does become get bit reduced after being scaled, it's not going to be that noticeable at all, especially if you plan to use them in signature pieces or even headers/banners. Actually, in my experience, that's the main way people use C4Ds. Sometimes they can be left at full size, but normally they're pretty huge and if you limit yourself in that regard you'd have to do a lot of C4D searching every time you wanted to use them, haha.
Also, I might as well give you a quick rundown of the different types of C4Ds there are. There are many ways to approach C4D usage, but it's clear that some methods work a lot better than others.
EFFECT C4DS [EX:
x] - I find that effect C4Ds are frequently used to add lighting effects. That being said, they're usually set on layer modes like Screen and Lighten to get rid of the black backgrounds. Rarely do I ever see them being set at a layer mode like Normal.
BUBBLE C4DS [EX:
x] - They are exactly what they sound like: C4Ds done in the shape of bubbles/circles. Again, these are normally set to Screen and Lighten. People are pretty big on lighting with bubble C4Ds as well.
ABSTRACT C4DS [EX:
x] - These C4Ds come in all shapes and sizes, and they can add structure and/or increase flow. Unlike the previous two types of C4Ds, I see them set to Screen, Lighten, AND Normal - this is because abstract C4Ds can be renders or have a black background.
WIREFRAME C4DS [No example because this is last minute and I initially forgot to add this, whoops] - These C4Ds are line-based, and are normally put on Multiply or Darken since the wireframe C4D itself is usually black on top of a white background. They make really nice backgrounds but they can be used for foreground/other details too.
ILLUSTRATOR SHAPES [used
here and
here] - Not exactly C4Ds per se, since they aren't created by the Cinema 4D program (as far as I know), but they are similar. I mainly use these to add something extra to the background and/or make some areas look a bit more busy. There are many other ways you could use them though, since the random lines are actually pretty flexible. Just make sure to transform it (rotate AND resize) to fit the graphic. Imo the best layer mode to use with these is Normal, since I feel like illustrator shapes should be an interesting and eye-catching element/feature, but honestly you're always free to experiment with whatever. Same goes for everything else too. I'd say that a part of design is breaking rules and seeing where that gets you; what I've mentioned about everything so far is merely the most common/widespread usage.
Ah, and you mentioned that you wanted pack suggestions in the OP, so I'll give you a download link to a collection I put together of C4Ds and illustrator shapes that I use most often: [
x].
Cam, asked me about this a while ago iirc so I thought I'd share it with you as well ;-]
Disclaimer - None of the resources inside the contents of that folder were made my me. They were merely collected by me.
If you want, give the contents a look through, to see if they'll fit with your style or not ;-]
If they don't, I recommend browsing deviantART by using the C4D types I mentioned above as search keywords. That will lead to an inevitable downloading spree, and I can guarantee that you'll come across a few packs you'll really like eventually. Good luck :-]