Ability to regulate, areas upon which laws are allowed to touch, period. In other words when they propose to take over this or that industry, you say no. When they propose to regulate the behavior of grown adults be it in the bed room or in the market place, you say no. You say no to every expansion of power beyond the enumerated powers in the constitution and whena judge interprets the general welfare clause broadly, you impeach his ass so other judges get the message that limitation of the states powers, not expansion, is their role.
Well over 90% of what they do. Writ broadly I'd axe government involvment in education, trade beyond a small tarriff on imports, interstate trade, health care which means getting rid of both medicare and medicaid, the FDA, the DEA and good amount of the alphabet soup of agencies, the IRS, etc., I'd scale back foreigh policy to be defense based only and only upon clear and present dangers, etc. In other words I'd like the government to stick to the enumerated powers listed in the constitution and leave it at that.
As to how to relieve them of those powers, you need to educate and convince the public that they are better off without the government dictating terms to them in damn near every aspect of their lives. As a practical matter the existing generations are already lost as far as I can see, I would target the educational system as I believe many socialists did in the past, and start teaching kids so when they grow up they are more skeptical of government power and more trusting of their own abilities to work things out voluntarily amongst themselves.