For vim/neovim users you can use digraphs, where you press `<C-k>` followed by a 2-character code to get a symbol (see `:help digraphs` and `:help digraph-table`).

For example,

    <C-k> -> gives →
    <C-k> => gives ⇒
    <C-k> d* gives δ  (greeks are generally all _letter_*)
    <C-k> D* gives Δ

Some of the combinations are a little weird to rememeber, but if you use them regularly then it's easy enough (like greek or arrows).