Can anyone advise on tips that my husband and I can do to avoid paying so much federal taxes each year? We have increase our 401k contribution, & changed our exemptions.

It depends.

If you anticipate everything staying relatively the same in 2020 as it was in 2019, you should compare the amount of your income taxes withheld on your paycheck against your total wages.  Then compare this percentage against your actual taxes due in 2019.  For example, if your total tax due was $10,000, and your total taxable income was $100,000, then your taxes were 10% of your income.  You can look at your wages, and see how much withheld.  Then compare it to what you are currently withholding and make adjustments as needed.

You will need to make the changes with your employer on a W-4 Form.

W-4 Form

If you anticipate changes in your income, you will need to factor the changes into your updates to your withholdings.