First time modder, looking for starting advice.
As for your second question, I'd definitely recommend working on the puzzles first. Puzzles are the core gameplay mechanic of the Portal series, so as pretty as you may make it, a map with a cube, a button and an exit isn't fun. Start out mapping on large grid scales, and don't pay much attention to which textures you use, just what's portal able and what's not. Then, when the puzzles done, you can add in finer details, rough things up a little - though I'd recommend not doing any overgrown or Wheatley-exams chambers yet, it's easier to start off with the basic, Clean ones.
Anyway, as I said, I think I went on a bit there, but I believe my points are valid. One other things is; there's a topic somewhere about the dos and don'ts of designing a map. Read through that, it's good advice. Enjoy mapping! I hope to see a puzzle from you soon. 
wrathofmobius wrote:
Something I found helps with fleshing out map ideas is to draw them out on paper. This will help you when you copy it over to Hammer and also to figure out any gaping holes with your idea. I agree with the previous post as far as choosing between a pretty or fun map, and I'll also add that I usually make the first version of my maps out of dev textures.
Well said. I don't know how anyone could just start a project without drawing a sketch, brainstorming or creating a WIP first.
Decide what you are going to do, then do it. That's so you don't spend endless amounts of time pondering what to do next. Also it sets a goal, so then you don't give up halfway through making it.> thesaxmachine wrote:
Also, what do you mean by dev textures, just to be clear, as in just basic filler textures?
The dev textures are practically orange and grey grid textures plus a couple of orange 'measured' textures for ideas on how to scale and texture your map. You can find these in the hammer texture browser by putting 'dev/' into filters.> thesaxmachine wrote:
I've tried drawing some basic puzzles out on paper. I'm running into trouble when it comes to trying to try a room with 6 walls of puzzle space minimum on paper in a way that makes sense.
If you ever did tech drawing at school you would do a bit of 3D work. I always draw in 2 point perspective, it might sound difficult but it is fairly easy.
If you find that you cannot do this, try drawing from the top view.
Also it's good to draw quickly and precise rather than beautifully. Use a ruler and make your own symbols for the different elements in your map. E.g. Have 2 B's connected by lines to indicate a fizzler.
For example:
```
[] = button
--<>-- = door
)---( = fizzler
```etc.
You can also make different sheets for cross-sections on multiple heights if your design is complex in the vertical direction, and even use formulas to make puzzle elements react to each other and 'test play' the whole thing before drawing a single brush in Hammer!
thesaxmachine wrote:
I just don't think 2-point perspective is letting me explore all 3 dimensions of the space since it will always leave at least one wall out, and top down alone makes it hard to create puzzles under a space and the ceiling.
You don't need to follow realistic rules in a diagram. You can have walls appear see-through to show what is on the other side of the wall. Here's one I prepared earlier. I bent my 'ruler rule' because there's no rulers on the computer.
Picture

thesaxmachine wrote:
...is it better to have an idea for a puzzle, make a great level design, and make the puzzle idea fit the level layout, or make the level design fit the puzzle design and hope it doesn't look boring? Another related question I have is if a beginning mapper should focus on making creative puzzles, or making great environments first. As someone who is new to both, I won't be able to do either great right off the bat, so knowing if focusing on one will make the other stronger will help. Any other first time advice is appreciated. Thanks.
i always make the level design fit the puzzle design. but that's just my personal opinion.