There are 6 rules I can think of:
1. Separate prefixes, suffixes, and root words EG. pre/view, work/ing, re/do, end/less, out/side.
2.If there are two consonants next to each other, divide in between them EG. buf/fet, des/sert, ob/ject, ber/ry, fer/ry.
3. You can't split 2 consonants that (when pronounced together) make only 1 sound EG. "th", "sh", "ph", "th", "ch", and "wh".
4. If the word ends in "ckle" divide just before it. EG. ta/ckle, fre/ckle, ti/ckle, bu/ckle
5. If a word ends in "le" without the "ck" divide from 1 letter before it. EG. ta/ble, ap/ple, rum/ble, fa/ble.
and 6. Think is the consonant surrounded by vowels?
A. Does the 1st vowel have a long sound? (Like the 'i' in line)
Divide before the consonant.
ba/by, re/sult, i/vy, fro/zen, Cu/pid
B. Does the 1st vowel have a short sound? (Like the 'i' in mill)
Divide after the consonant.
rav/age, met/al, riv/er, mod/el, cur/tal
I hope these clear it up a little for you. It may sound complicated now, but it's something you learn to do without thinking about it.