The main thing is to plan ahead.
Take time to draw out the diagram.
Then layout the parts (keeping the logical things together), then think about it.
Only once you are sure it is neat, and that you have enough room (and space to add more things- YOU WILL THANK YOURSELF LATER!)
Then as you wire, take your time, and tick off each wire on your diagram as you connect it.
Make sure you leave lots of excess slack in the Slotted Trunking. Also Stranded Cable is a Must between the front door (if you have switches/etc), and also stranded wires between components (in the Slotted Trunking). Ferruling the ends of the stranded wire is a good idea.
Also, it is always better to number the wire ends, and then to put the same numbers on the diagram (and Keep the diagram in the Panel). It is a waste of time going to site to fix a fault, and finding that you left the diagram at the office, or having to get the people to run the place to hunt around for the diagram for you, or having to reverse-engineer what you have done previously.
Here is one (the neatest one), of several panels I recently did at a local nut processor. - This is before I installed the Labelling.
They are all Direct-On-Line starters, so it is not too complex.
You can see that there are only 10 starters, but you can see it is a large box I used (to allow for expansion). I also installed the additional Trunking and Din rails for future expansion (Saves time and mess later),
also I drilled an additional 10 off 22mm Holes in the front of the panel, and put in blanks. That just means that in the future if they want something added, it just means putting the contactor/overload in, and then putting the Illuminated Start/Stop combination button in, and wiring it up (some spare cores in the loom to the door would have been better). But this way, when something is added, we do not have to come and Drill/Grind, etc, as this this a food processing (nut) factory, you absolutely CANNOT have any iron filings, etc going around whilst they are processing.