Ideally you want a longer chain to match the larger cog. Also you will need to adjust the B screw on the derailleur to clear the 28T. Barrel adjuster tweaks will depend on on how closely you can match chainline on the 2 cassettes. I run 2 different brand of wheels with a 12-27 and 11-28 cassette on my cross bike and don't need to do any adjustments because the spacing is the same so I don't touch the cable and I just leave the B screw set to the 28T.