If you mean hacking tools, such as nmap and programs that you use, you can just whitelist them like ca0s said.
If you mean to send to other people, you will need to crypt/pack the virus you're sending, it's not as easy as it sounds, because every AV has a different way of detecting malware, and then you also have the runtime and scantime detection.
The easiest way is to obfuscate the code, by adding lots of junk.
A program that does:
Edit Registry
Delete Files
Copy to startup
Will be almost always flagged as virus.
However if it does:
Edit Registry
Open firefox in a page
Create files (with version, and author and stuff like that)
More random code...
Delete Files
More random code...
Copy to startup
More random code...
It won't be detected as much.
Also try to avoid using pre-made functions, sometimes something as simple as extracting the function code and using it won't be as detected also.