Personally i took jumping always as my favorite method. the reason is that you just need this one little millisecond during which you have to take the decisive action. you just need one short decision and all is decided. after this short moment you can't do anything else. thats the advantage. once the decision(the jump itself) is taken everything to achieve the aim(to ctb) is done. no more return, no more si that could hinder you. with other methods there is a lot of time in which you can return and stop your project and a lot more probability to fail. as i was afraid not to be able to organise well other methods, i still have jumping as my favorite. when i thought about other methods there where different things in which i didnt had the self confidence to succeed. for example hanging: putting the not athe the rigth place and so had the tipical symptoms of chiking instead of just ctb by lack of blood. co: not to produce enough and end up like a mental vegetable and therefore being in a situation thats worse than my actual state. n, sn or others: same as with co.
about jumping i think the most important is to be sure to have enough height and a good underground (i think not less than 100m, hard underground). another advantage of this method. lostallhope.com gives some ideas
there are other things to consider if one wants to:
people around that could be shocked seeing someone killing him or herself.
people (e.g. police, firemen, medics) that have to pick up your remains.
the fact that there will be roads, railroads and so on closed for at least some hours because of your action. keep in mind that there can be hundreds or even thousands of people affected by missing their work or plane or train... if this is good or bad, i don't know, depends on what you think about the daily running of this society...
these where just the most imortant considerations i think.