Jack of all trades are usually masters of nothing. All these "fixes" people do to their homes on a budget more often than not compound problems because they don't know what they're doing. Most trades people don't either, that's why it's best to start with a blank slate and Keep It Simple Stupid.

Adding attic insulation doesn't stop air leakage or control moisture. You just end up with more dust coming through your wall penetrations. Things like attic fans do nothing but jack of all trades are all to happy to take your money and install them.

Once you start sealing these leaking homes up all that dirty air coming through every crack no longer supplies the air that's being burned up by the furnace, hot water tank, or exhausted by the stove exhaust. You have to add makeup air which introduces a whole bunch of other issues which don't get addressed on a budget.