1) Here are website links for the state and localities of some items for service sales tax in PA state and local for us to start the discussion.
Among them, the editing services could be close to your category of services. Because you locate in PA, you need to collect sales for PA if you verify that part of your category of services falls into the tax category. Please also verify the county you live in and the counties of PA you provide services in and their regulations.
2) For another example, the State of CT tax consulting services. Then, your career coach services provided to that state may be subject to the collection of sales tax. See http://www.ct.gov/drs/cwp/view.asp?a=1477&Q=269930&drsPNavCtr=
3) Sales tax on services is a new way for the taxation authorities to broaden the scope of their tax bases. Every taxation authority has its own regulation on who and what services are subject to tax.
4) It is suggested here that for each state you provide services to, at least once a year, verify the new rules and regulations and document your result.
6) There are sales tax software programs. If you subscribe to one or purchase one, then supposedly, the software can update the rules and regulation for you and submit on line your sales tax reports to various states and localities. Once you are used to it, you simply add it to your invoice and make it one line-item. Your customers at the taxation state are used to be collected for such taxes.
So called "sales tax on services", by definition, should not require physical equipment or work product.
If you frequently travel on the road, you need to carefully keep record of your whereabouts. The state you travel to may literally count the days of your presence in their states to determine whether you should have collected the sales tax for them. Traveling exhibitors have such historical issues in their industry. One state may give exemption for presence in their state for one day. Then, the presence of more than one day makes your business being required to collect sales tax and pay over to that state. For example, Arizona has a threshold of two days of presence, "An employee present in the state for more than 2 days per year". http://www.taxjar.com/states/arizona-sales-tax-online/#do-you-have-sales-tax-nexus-in-arizona
Please feel free to follow up.