Dressmaking doesn't pay particularly well for the amount of work involved - you need to price the work properly and get a decent deposit.
Another problem is that people will buy cheap fabric that doesn't suit the pattern, and expect a couture dress.
Bridal wear - relative got commissions from, shall we say, 'curvier' customers who couldn't get off-the-peg to fit. You might need to explain that a style might not suit or advise on foundation garments.
Not a relative, but I know of one dressmaker who had very nearly finished a wedding dress and the customer took it away saying the work wasn't good enough, and didn't pay for the work, so basically they got a made-to-measure bridal gown for a small deposit.
Alterations are your best bet. Taking in and letting out, repairs, darts, hems etc are much less time-consuming and people are willing to pay for your expertise. Don't do jobs for nothing for friends, it encourages CFy.
When pricing, factor in time, expenses, raw materials and equipment. You may already have things like sewing machine, overlocker, scissors, elastic, thread, hooks, zips, interface, etc, but they mount up.
I wish I could sew properly.