Hello, my name is Quinny and I am a former Mod+ and Map Judge, so hopefully I can also offer you some additional helpful advice--
I specialize in "cute" organics (but I have made maps of all kinds, including intricate structures) and I dare say I am a pretty good mapmaker. All maps of mine are listed below if you would like to take a peek at any of them. I have also taught and actively provided feedback to mappers both as a judge and a fellow mapper in the past.
Q: For those who want to make a solo map but struggle with building good looking structures / other bases for pk to go onto what would you suggest?
A: I definitely agree with Pres as far as picking something to make of your own accord. If you aren't experienced with building tools such as WorldEdit, take the time to familiarize yourself with them completely and thoroughly. I have an intro guide to WorldEdit on my 25th plot (/plot v Quinnyp 25) if that interests you at all.
I would also add that there are different ways to build and all of them are valid, as long as you come out with a good looking product. People will offer you advice on how to build, and you should familiarize yourself with them and take what works for you and roll with it. I would say that practicing building and asking others for feedback often is key to seeing improvement with your builds. Hanging out on the Creative server and free building that way is another way to practice.
Q: What difficulty pk would you suggest someone makes as their first and why?
A: I'm in agreement with Pink and Pres once again, but I would lean more toward an Easy map. Start with a small build, and an Easy map really only needs less than 30 jumps to serve it's purpose. It's a small enough scope where you won't be overwhelmed and burn yourself out trying to edit and revise the course.
Q: Any specific examples of maps to look at for examples of good pk (any diff)?
A: I don't have any specific examples to offer at this time because I think that learning how to critique and assess maps is a major key in learning to improve your mapmaking skills. Just like anything else, you should immerse yourself in ALL of mapmaking. Pay attention to the Submissions forum. Read what players, mappers, and especially judges have to say about each map.
The Submissions forum is practically a free and accessible, rolling master class on mapmaking. Go to look at the maps in-game. Look for the specifics of what the critiques are talking about. The more you do this, not only are you collecting some experience alongside other mappers but you are also familiarizing yourself with what others are building, how they do it, and how they improve it. Following maps that are in Reviewing will also be helpful, as maps labelled as Reviewing have GOOD qualities to them, but lack something that is necessary to make it worthy of being accepted. When they make changes, try to pick out and NOTICE what those changes are. Were they the right adjustment for the map to be accepted? If so, learn from that.
If you were to look at specific maps that are only good, there's the intimidation of needing to meet that level of quality immediately. While yes, having your map being accepted is something to strive for is obvious, learning to consume the maps that are "poor quality" is just as important. Learning what not to do helps you learn what to do.
Q: What is your pk map making process?
A: 1. Referring to the Parkour List to make sure the theme I want isn't too similar or hasn't already been done before.
2. Looking for reference photos to better understand the concept OR the character that I am trying to create. Look at poses and position of objects while having a path in mind already while doing this. Try to come up with a design that makes pathing easy on yourself when you are ready to do so. This is easier to show than to explain.
3. Create the build out of spheres (those who know me and how I build know that I build mostly with transforming/altering WorldEdit spheres, and I chisel away or add onto the shapes like carving marble).
4. Create a path. I do this with an understanding of how I want the jumps to flow (I will talk about this below).
5. Create jumps. Test in chains.
6. Revision. TONS of revisions.
7. Have testers online come to give feedback.
8. More Revisions.
9. Submit and profit!
Q: What do you keep in mind the most when you make maps?
A: There are MANY MANY things that I keep in mind when making maps, but the one thing I should emphasize is not building your parkour jump by jump.
Well now, that just doesn't make sense does it? Isn't the point of parkour to jump successfully? Well, I'm referring back to the concept of flow. The best way to create parkour that is dynamic, interesting, and suits the difficulty overall is to understand the concept of flow. When I create parkour, I am not thinking "I want to include this jump, then throw in this jump, etc." I am paying very close attention to the build and asking myself, "how will the player get from A to B?" This line of thinking accounts for the build, the path, and also allows you to create the course more holistically and allow the difficulty to remain consistent throughout.
When you test a map, you should be trying to chain as many of the jumps as you can together. This is how you assess the flow. If it feels choppy, abrupt, or one jump sticks out from the rest as being annoying to a point it breaks up the flow of the course, change it. This is the best offering I can give you without even stepping into game. One map I can offer as an example to this is my racing map, TaikoNoTatsujin (Medium).
Q: Any other things to suggest?
A: Those who know me know I have always been willing to go above and beyond to help other people improve at building and making parkour. You are included in that! I don't log on as much as I used to, but that's mostly because I burned myself out throughout the course of the pandemic. Know that if you want feedback or assistance, or even just some tips on building organics, things like that, I am more than willing to help out. Message me on Discord: Quinny#2316 if you ever want to discuss.
Those who are willing to learn are the best people to teach! Thank you for asking thoughtful questions, because it's guaranteed there are other non mappers who are interested but don't know where to start. Hope this helps!