This is just my own experience - I am offering no advice or comparisons for others.
I traded on the floor as an independent, commercial energy, prop financials and energy, and for a HF over a period of thirteen years - all out of office buildings in Chicago. I had also been a steady and frequent ET contributor since the site's early years (before there were "likes" and when there were quite a few professional traders contributing). I had dozens and dozens of PMs sitting in my ET inbox from experienced traders asking me to teach them how to spread trade over those years. This was especially true for traders who had made their way to prop firms. There came a point where my kids made it into grade school, my wife went to work downtown for IBM and I decided to trade my own account out of my home office - and it was at that time that I decided to start taking on just a few clients at a time and to teach them how to spread trade properly.
My point being, speaking for myself I just literally fell into it because I had all these guys begging me to do it at the time. The Chicago prop firm scene was very strong at that time and most of the big earners at those groups were (and are) monster spread traders. I was one of the very few spread traders who had an established trading background and who freely posted and helped other members here on ET.
Doing client work is not free money and it should not be taken lightly. You have a fiduciary responsibility to see your clients through. If you have a client working on a Singapore or London prop desk that means you take "Go to Meeting" sessions at some very uncommon hours for you. Many clients are a joy to work with but some clients will test the limits of your patience and interpersonal skills. Screen them well and don't be afraid to wish someone good fortune but then politely refuse them. There are some personalities that you just do not want to deal with in a client-mentor setting.
It is a very gratifying feeling to see your clients do well. It is thrilling to take a phone call from a prop firm principal telling you that he has hired one of your former clients and is asking you to send your future clients his way.
It is a shitty feeling when you take on a client, and then subsequently find out that they have the work ethic and motivation of a tree sloth. You cannot fly 1,000 miles, force a client to review all the materials you provided, and build out their charting platform for them. You can't force clients to paper trade your system and to set up weekly meetings with you. You wonder why they bothered, and it truly feels like a waste.
I really believe that more traders should be spread trading. I feel very passionately that spread trading is an under-utilized strategy in the retail and smaller independent trader community.
You will never have 100 percent client satisfaction. But if you don't do good work for clients, if you cannot create a pool of satisfied and profitable clients - you won't last long and you won't have any references. For 90 percent of my clients it is the references and not the ET ads that led them to my doorstep.
Just my own two cents, YMMV.