1) Start out by drawing and measuring your planned area.
2) Purchase your flagstone, make sure to purchase extra for areas that may need to be cut or for ones that you may not like.
3) Dig out your area about 9" deep and about 12" beyond your ending area.
4) Make sure your slope going away from your home is 1/4" per foot. Example a 12' patio there would be a 3" difference from top to bottom.
5) Place stabilization fabric directly on the dirt and 4" - 6" of 2a Modified (crusher run) above that. You will need to run a compactor over the gravel.
6) Install 1" of stone dust to be used as a leveling agent for the flagstone. Screened the fines with a pipe. If it is going to rain make sure to cover the fines with a tarp.
7) Hammer spikes across from each other and attach a string line this will help keep your lines straight as your installing the stone.
8) Start against the house laying the flagstone using the stone dust to help level out each one. Make sure you have your rubber mallet in hand. You will use it to bang on the stone to help place it.
9) Once you have your flagstone installed you will want to install paver edge restraints and polysand.