There are various changes that I think could make universal credit work better for low income families.
Removing the two child cap would be a huge step in reducing child poverty. As would removing the bedroom tax.
Reducing the administrative burden associated with universal credit for working families would be a big help. The endless uploading of evidence is wearing.
One thing that would work for a lot of families is looking at how child care costs are supported.
Rules like not being able to claim for costs paid more than two assessment periods in advance block a lot of claims for care in school holidays where camps/clubs fill up fast.
Top up fees/consumable charges etc are considered optional by universal credit but for places providing childcare these are essential and not optional. This means that I can actually only claim back up to 66% of my childcare costs through universal credit and a lot of people I know have it worse than that.