Well, not knowing what gage your gun is, I will just suggest that you start at about 65 gr. of powder, with equal volume of shot.
In my 20 ga. for my turkey load I use 65 gr. 2f, 3 overshot cards, 1/3 to 1/2 lubed felt wad, 1 1/4 oz. #5 shot and one overshot card.
You will need to experiment and see what your gun likes. Chose a starting point and fire a test pattern. Then start varying components, only vary one component at a time, to find what works best. Go up in powder in 5 gr. increments until you get the best pattern, then try some different powder (if you were using 2f try 3f, or vice versa). Next vary the over powder cards. You may want to try overpowder cards and overshot cards. If you use overshot cards, try different # of overshot cards. Don't be afraid to experiment. When you get your best pattern with that, start experimenting with the wad. Use no wad, 1/4 wad, 1/3 wad, and 1/2 wad. Again find what gives the best pattern. Then vary the shot. Start with 1 oz. go up and down and see what works best.
Eventually you will find what your gun likes and you will have a good excuse to go burn some powder.
All this makes for a fine day at the range.
I also suggest that you read Bob Spencers "Blackpowder Notebook", lots of good info in it.
http://members.aye.net/~bspen/
Good luck and have lots of fun.