The only role in life that may be more important than that of "father" is "husband." With that in mind, let's review some ideas to help you be a better father.
Love their mother
As a father, the most important thing you can do for your children is to love their mother. If your marriage has already ended, show her respect. There is little of greater importance to children than the relationship between their parents.
There really is no way to make up for time with your kids. There will eventually come a day when they don't want to spend as much time with you. It will come suddenly with little warning. At that point, it is almost too late.
Tell them you love them
If you get into the habit of telling your children you love them when they are small, you can keep the habit when they are grown up. They'll appreciate it every time you tell them.
Be a good example
No one is perfect. Your children understand that. They want to see you strive to do the things you teach. Walk the talk.
It is a father's responsibility to teach his children how to behave, to set limits, and enforce them. Your kids expect you to do it; they won't love you more if you don't. They may claim to "hate you" when you do, but in the long run, they'll thank you.
Never abuse them
Don't ever abuse your children or your wife in any way, physically or emotionally. Don't justify yourself even once. If you ever violate that trust, get help.
There will always be conflicts between your responsibilities as a provider and a father. Finding the right balance between your work and family requires thoughtful priority setting and consistent application of those priorities.
You have a responsibility to provide for your children. This responsibility doesn't end with your marriage. Don't ever shirk your duty to provide food, clothing and shelter for your children.
Your children's future opportunities will be severely limited if they cannot read or fail to finish high school. Take personal responsibility to ensure that your children read; require them to finish high school, and prepare them for college.
Help pay for college
Even if, you are not wealthy, there are things you can do to help your children launch successfully into adulthood. College is the number one thing you can do to help them. You don't have to be solely responsible, but help shoulder the burden. If nothing else, let them live at home and attend the local college.
In the end, nothing will bring greater satisfaction than being a good husband and father. At the same time, remember that it will be hard. There are no "do overs" in parenthood, so be the best father you can be.