You mean you don't know how to mana-weave? Tisk Tisk. If you're good at it, it should look like your table shuffling, then make 1 riffle shuffle to make it look not so suspitious.
your table shuffle should be 6 piles, after every 2 spells you put down in each pile you should lay down a land. Depending on how good your riffle shuffle is it shouldn't mess up your land distribution too badly.
next we have a mana curve... here is a sample:
1cc- 16
2cc- 12
3cc- 4
4cc- 4
Now for instance, let's say this is a 2 color deck. We have a a good mana curve that should allow us to run smoothly on 24 land. But as always, bad luck can play apart, and is to blame most of the time if your gat mana ****ed (mana-weaving can fix this if you don;t mind scheating). But don't cheat because it's not cool.