I guess the real question is, what type of side work are you looking to do? If you want to sign and seal some plans, you should look into insurance. Also, make sure you aren't using your employers resources to do work on the side, they don't usually take too kindly to dropping a thousands of dollars on software for it to be used to make their employees profit. If all you are wanting to do is provide advice and some consultation, then that is a lot more easily done, but of course you will need to build up a client list. They will have to know you for your work and will call upon you when they need something done. Unfortunately, in this game, there isn't a line of people out there holding onto paper napkins with some land development ideas on it looking for an engineer waiting to take their money. You have to build relationships and demonstrate competence and ability and become a known entity.