In terms of fundraising for nonprofits, most of the general nonprofit resources above have lots of information about finding and securing funds. But if you are looking for private funding there is no more important resource than Candid’s Foundation Directory. The directory includes a massive index of nearly all private funding institutions in the US. To access the directory, you must either pay for membership or access it through a library.
For federal government funds, the best source is the aptly named Grants.gov which is a clearinghouse for thousands of US government grants and RFPs, as well as information on how to apply. Keep track of what funding is available from your state through departments concerned with public and behavioral health or other social services.
If you just want to learn more about the study of fundraising, here is a great overview from Ashley Whillans at the University of British Columbia. Here is a blog post from 501Commons that shares many fundraising resources including books, strategies, and tools, and here is another from Global Giving that runs down some of the most important fundraising tools for nonprofits.
It would be a serious omission not to mention two of the oldest supporters of harm reduction work- both the Comer Family Foundation which was the very first private foundation to take a chance on harm reduction direct services and the AIDS United harm reduction initiative.
If you are looking to develop or manage your conversations with donors, check out Mailchimp, which helps you design and manage email interactions. There are also multiple services that will help you with donor management and development including the nonprofit services of Salesforce and Network for Good. You might also consider Donor Box as an alternative to PayPal or other services for collecting donations, especially recurring ones on your website; they work exclusively with NPOs and their fees are significantly lower than other services. In addition, Hootesuite, which allows users to manage their entire social media presence at one site as well as automate certain aspects of that presence at a discount through their Hootegiving program
In terms of financial software, the biggest platform in the world is Intuit’s Quickbooks. Quicksbooks is offered as both a desktop and online version. Of the two, the online version, a subscription service, has more robust support. Intuit has grown their market share in large part by offering a lot of training and support to make it easier to use their software. They run a payroll service which will file your payroll paperwork and taxes for you and even offer monthly bookkeeping services for a fee.
Another great option for payroll is Gusto, which includes payroll services but supports a suite of other employee benefits such as insurance and savings plans.