NetRadiant 1.5 for OpenArena Cheat Sheet by NeonKnightOA

1. Thou shalt ALWAYS plan your map before opening the editor.
Remember to also bear in mind the limita­tions of the game you're mapping to (physics, weaponry, etc).
2. Thou shalt NOT place KEY GAME OBJECTIVES (flags, obelisks, control points) in areas only reachable throughout trickj­umping.
It creates unnece­ssary imbalance giving unfair advantages to humans, especially if they involve trickj­umping. Key game objectives should be available to everyone on equal foot, regardless of skill level, PERIOD.
3. Thou shalt NOT make trickj­umping mandatory in order to navigate the map.
Try to get scale right before sitting down and doing things. Maps should be navigable by both humans and bots. And speaking of botplay, refrain from sealing areas of your map for specific gametypes, as they may confuse the bots!
4. Thou shalt ALWAYS handle weapon­/item placement with care.
The powerf­ulness of the weapons should match how riskful is to get them. The players should work hard in order to get that sweet BFG of mass destru­ction! Also refrain from placing ammo near their respective weapons or too many powerful items at near-d­ist­ance.
5. Thou shalt NOT limit the powerf­ulness of overpo­wered items by modifying the item's proper­ties.
Doing so messes with the player's natural timing of the items. Better limit the weapons' powerf­ulness with the map itself.
6. Thou shalt NOT go overboard with (and abuse) dynamic features (traps, movabl­e/t­rig­gered platfo­rms­/"tr­ain­s", doors...) or shaders.
They hurt the flow of your map if handled in a careless way. Bear in mind the limita­tions of the game (frame­rates, connec­tivity, etc) and be smart and conser­vative with them! Also, tons of transp­arent and stage-­based shaders make your map's perfor­mance slow as hell.
7. Thou shalt NOT rely on global ambient lighting
It. Is. Lazy. Ambient lighting makes the map look washed up. This, however, doesn't mean that your map also needs to be dark. Take your time to lit your map properly and adjust the map's lights until it looks reasonably well lit without looking too washed up.
8. Thou shalt NOT unbalance asymme­trical CTF maps
Give the same weapon­ry/­itemry to both teams. If a team has an advant­ageous feature then work a counte­rfe­ature so the other team can stand against their enemies. After all, "­balance in a multip­layer map means symmetry in opport­unities to win, not necess­arily layout­".
9. Thou shalt NOT force your map to work with any gametype
Better start with one main gametype and then add the gametypes it can support without problems.
10. And most important of it all: THOU SHALT MAKE SURE YER MAP PLAYS AT ALL!
Nobody (except server trolls) wants to play a map which crashes the game.

1. Thou shalt ALWAYS use common­/caulk for new brushes
It saves time by you only needing to texture the sides of the brush you want. The options Clipper tool uses caulk and Always use caulk on new brushes are your friends.
2. Thou shalt handle patches with love
If you want to create smooth curves, patches are the most efficient way to go about this. Also, patches get along well with Hint brushes. Also, you should use Bevels instead of Endcaps or Cylinders. Vertex manipu­lation is your friend!
3. Thou shalt ALWAYS mapmodel thy complex decorative brushes if ye need to use them a lot
If the "­mod­el" is compli­cated and cannot be easily created via brushes then use models. No second thoughts.
4. Thou shalt NOT make a map composed by over 90% of structural brushes
Bad use of structural brushes adds compil­ation time and screws up VIS, making the game to render what it isn't supposed to render. The only brushes which must be kept marked as Structural are those which seal the map from the void and those which are meant to block VIS. Everything else must be made detail.
5. Thou shalt ALWAYS use the brush clipper and vertex editing tools instead of CSG Subtract and CSG Hollow.
CSG Subtract and CSG Hollow are lazy tools which create more problems than necessary. Manual modifi­cation of brushes is a far better option, as well as it being slightly better for optimi­zation purposes. Not to mention that it will look a lot cleaner too.
6. Thou shalt ALWAYS match the vertex points of thy brushes and NEVER use grid sizes lower than 8.
Unless you want to painfully deal with T-junction errors, sparklies, and all kinds of avoidable glitches.
7. Thou shalt NOT abuse of doors, areapo­rtals and hint brushes in thy map
If your map has overdraw problems, you can use them mainly for VIS stage optimi­zation in creating clever portals so that large portions of a map that you can't see does not get rendered. Incorrect use of these tools can produce worse results instead of better results.
8. Thou shalt NOT workaround thy leaks by encasing thy map into a hollow block
With leaks, better seal the hulls yourself (use Pointf­iles). With skies, better reduce the space and use sky shaders, otherwise tris count will get high! In other words: FIX THY LEAKS, YE BASTARD!
9. Thou shalt name thy map differ­ently for every new version released.
Naming conven­tions (a3, b4, v2) also help trace bugs with newer releases which weren't in the older versions.
10. Thou shalt ALWAYS include an .aas file with thy map
The odds of your map ending up in a server you don't own are close to null. With BSPC doing the job for you, you have NO excuses. And even when there are issues with limita­tions, there's a way to workaround this.