ok here is just a couple of strategic procedures I use when editing in Geo-mod
1. when drawing regions:
completly lay all settlements and ports first (worry about everything else later)
then when you have a complete map working go back and edit for every region`s say religion, once you that is fine go on to the next thing such as rebels and then music for all regions and then finally begin editing settlement sizes, buildings and if it is a castle or not.
Last thing now you set your faction ownership for each region
why? work this way? trust me it will keep you on track of the exact place you are in your modding! I have had in my own expirience thrown weeks of work away because I could not remember exactly what I was doing.
also when drawing ground types (in my opinion) it is best to draw them after you have laid all of your regions, simply click view cities and ports and you can avoid errors in placement easily.
2. now if your map is done! you can edit all of the specifics you can in Geo-mod such as win conditions, econmic style, start money and kings purse.
once all of that is done you can now go onto the hardest part of using geo mod (not so hard but you do need to be very focused) which is, Garrisons
for all regions I suggest testing after every new general and army is placed!