I have a limited company that I do consultancy through, and it has been very useful to have it pick up legitimate expenses like travel and new computers. I’ve set my rate high to discourage boring people from tempting me with stupid projects! I retired at C level so I was paid more than I deserved. I take that rate, uplift by 50%, divide by the 220 days that very theoretically would represent the work year maximum I’d work and divide that by the six hours maximum per day I’d want to work. That gives a result that I then tweak further up or down depending on if I feel motivated actually to do the work! As a result, I don’t work much, but when I do it is very well rewarded. It all depends on whether you need to do some work or really want to do some work. The more you need it, the more realistic and reasonable you need to be. If you really don’t give a hoot, like me, aim high - be happy when you get turned down and be happy when you get an engagement. The same for travel time - if you really feel like doing the job or need to, wrap it in and make them feel like they aren’t being nickel or dimed. If you don’t care about the job, charge and charge again! The real key about this is you - is this a necessary part of your financial equation or is this a hobby?
I started consulting 10 years ago. The income from my consulting has fluctuated wildly, however, the benefits and frankly very interesting projects have kept me at it that long. I won't work for anyone as an employee again, or if I do, it will be for a very short duration.
I charge what the market will bear. If my client is a non-profit or has a set fee and I want to do the work, then my rates go down. If my client needs something quickly and/or they are for profit and I end up educating them such that they could do what I did for themselves if they actually listen to me and use the tools I develop, then they get charged more.
However, here's the crux. When you talk X per hour and then haggle over the hours, you are haggling over the overall price. I have slowly moved my business charging philosophy to a value based one, or a fixed fee arrangement. When a client contacts me, we discuss what they want and then I determine what I consider a fair price for the effort. I then spread out a monthly payment with a 25-30% retainer at the start and then do the work. I then manage my own hours and effort. I also make sure they have something tangible at the end: a report, a presentation, an algorithm, etc. My rates have run from $75/hr - $500/hr based on how much time I actually had to expend on the project. The average nowadays is $125-$200/hr if they insist on an hourly rate.
Travel is always paid by them and is merely a reimbursement. I will use their preferred airlines, hotels, rental car agencies, etc, as it is a good will gesture and makes it easier to justify the expenses if they are similar to what their employees have.
I am a registered LLC in one state and have an EIN. However, the US gubmint doesn't like that and has changed it such that a sole proprietor LLC is treated like a pass-through and they want my personal SSN. I still use the EIN when submitting my estimated taxes and when I pay any other checks at the end of the year for my business or Schedule C purposes.
I do use the home office deduction on my taxes, and I do have a home office (room that is an office). They've made it easy in the last few years by giving you the option to use their simple $600 or so deduction. I deduct half of my Wifi and phone charges as well. I've set up an SEP IRA and contribute to it religiously (although I am now trying to transfer as much to the Roth as possible). I deduct my healthcare and dental insurance through the 1040 on the front as a business expense.
I am fortunate that in my consulting niche I get paid for my thinking - my credentials and experience have given me this opportunity. I have a website, but I do not overtly market - I am sought out by my clients for the most part. I am fortunate to have an international clientèle, so that I travel to Europe on business and can expense that travel. I usually tack on a few more weeks for an extended vacation after my business meetings.
I met a person who owned his own business a few years ago and he had the best advice: declare *all* income, however, expense all that you can as well. I've never been audited and have usually been very close on my income tax estimates.
I am semi-retired and if I can I may consult for many years longer. I do it for the intellectual stimulation and challenge, not necessarily for the money. I do like the tax advantages it allows, though, such as being able to expense my 'newish' (refurbed) computers and phones as well as the travel.
In any case YMMV - by the way, I quoted this person's response to the OP because I agree with them and think it is valuable advice to the OP.