Link by concept rather than by exact match. I will often explicitly have a See also: (some concept) link somewhere if I feel two subjects are closely associated. Linking new knowledge to existing knowledge makes it easy to remember. This has helped me find really cool connections on numerous occasions.
Name notes to be as simple as possible. I prefer using verbs or nouns to make it easier to link concepts and thoughts.
Good search matters a lot. When I search, I usually don’t know the exact name of the thing I’m looking for, otherwise, why would I be searching for it in the first place? I use search as an entry-point into a single node, then recall by associativity rather than by indexing. But having a good entry-point can make or break my flow into finding what I’m looking for.
Try to only add notes to the Digital Garden that link to content that already exist. This prevents storing irrelevant information and helpts link new concepts to already gathered notes.