Only two tips come to mind offhand.

First, get as many plugins, extensions, and nodes as you can justify. Even things only remotely relevant can prove useful once you start laying out a node graph. More options is more possibilities you may not have otherwise come up with so it's always useful to have as many as you can laying around.

Second, and this is specific to API's, set limits and throttle your calls when using Knime. It can handle loads of data and do amazing things with it, but it can also fetch it at such speeds that you can get yourself auto-banned from servers likely just from security policy violations. It's a huge pain cause some will ban your whole IP and lock your account. In most cases it seems to be automated and whoever manages things usually isn't even aware you got booted. So, be mindful of the rate you make these API calls and what the API you're calling allows for to avoid a lot of potential headaches :)