Added comment about coinbase maturity
Set up genesis block

Instructions from bitcointalk.org:

After you are done, save it. Now the genesis block will not match the hash check and merkle root check, it doesn't matter.

The first time you run the compiled code (daemon or qt), it will say "assertion failed". Just exit the program, go to
config dir (under AppData/Roaming), open the debug.log, get the hash after "block.GetHash() = ", copy and paste it to the beginnig of main.cpp, hashGenesisBlock. Also get the merkle root in the same log file, paste it to the ... position in the following code, in LoadBlockIndex()
Quote
       assert(block.hashMerkleRoot == uint256("0x..."));

recompile the code, and genesis block created!

BTW, don't forget to change "txNew.vout[0].nValue = " to the coin per block you defined, it doesn't matter to leave as 50, just be consistent with your coin per block (do this before adjust the hash and m-root, otherwise they will be changed again).

Also you need to change the alert/checkpoint key, this depends on the coin type and version, you can find it in main.cpp, main.h, alert.cpp and checkpoint.cpp.