Greetings Acer, and welcome to LMR.
Tips? The little "Search page" link on the right has hundreds of them :)
Here's a couple of mine:
1. Click the rules link at the top of the page and read it first. Folks around here love it when new members RTFM as it were :P
2. As far as the arduino goes, do you have a way of uploading sketches to it? Usually a spare UNO or an external programmer is used. (unless your "free-form arduino" is getting an FTDI chip)
3. If you aren't very experienced at soldering, you might consider using a heat sink clip on the atmega chip, so you don't cook it. Or solder a socket to the free-form circuit and plug the chip into that.
4. Other than that double check pinouts before putting power to anything.
5. Just have fun with it, they are tough chips, you almost have to try to kill an atmega.
Thanks Jerz for the tips, I know LMR and been using it since last year. Yes I will be using a ftdi chip. Socket is a good idea.