well the very first thing i do is go out and find a safe sunny spot.....this can take a while so google earth helps a TON on finding a spot in your area. after that you need to search the area a couple of times each week to see if there is any pattern in public traffic or maintenence (depending on location).....and if questioned why YOU were there always have an excuse you can back up.

Next i decide weather im going to start from clones or seeds, and if i will plant in the ground or in camo'd pots. if starting from seed you need to plant after the last frost in your area. you will also need to find a strain that will finish on time in your area.
whether your planting in the ground or pots QUALITY soil is what you will need. You could amend the ground you have or buy potting soil.

find a way to get water to your plants. This is one of the biggest problems in gurilla growing. lugging abunch of water a couple times a week is going to look very suspecious, not to mention back breaking. Look for nearby streams.

find a way to get your harvested plants out safetly

this is a vague idea of what you should be thinking about, there are deff. a lot more things but you can find that info around here.
good luck