i started a coule of years ago,
getting into it now,
its more technique than thrashing it.
the more times in a week you do it the more it clicks or is easier to analise and correct.
swimsmooth have a good book as well as the video and the book "swim speed secrets" by sheila taormina is very helpful.
swimming open water instead of the pool is something else,
like comparing fells to the road
there are quite a few tris that involve off road/fell runs.
220 mag is quite good for info but the prices of tri are very scarey.