A big consideration is not to make large pre-tax contributions to retirement accounts in the years of relevance to FAFSA (ie starting this year for a HS junior). The contribution gets added back to your income but you don’t get the benefit of the tax paid being offset against your adjusted income.
Better to add to your retirement accounts with post-tax contributions (Roth IRA/401K?) or if that’s not possible just put more post-tax money in a 529 instead of saving for retirement (if you’d otherwise need to make IRA withdrawals to pay for college). Or just accumulate more post-tax assets (counted at 5%) instead of having to withdraw money as income (counted at 20%) from your IRA during the relevant FAFSA years. But spend those assets down quickly to avoid them counting repeatedly across multiple years. Unfortunately you may not be able to sustain this until your third kid goes to college.