The Spine cone bomb, Fiery Vaporizer, and Blast bomb are all good lines to choose. (if you purchase the expansion pack you can get a strong shadow type bomb)

The Demo armors are good choices to invest in, basically any set that can increase your Charge time reduction.

The best strategy for bombers (and any player) is to actually take a bit of time to observing the monster's attacks. Some dash, some jump, some follow you, some sit in one spot, several have certain animations that signal them using a certain move. Knowing where a monster is going will help you know where to put a bomb.

Example: Kats are ghosty little monsters that can spit bullets, bite, and dash around. Trying to put a bomb beside a kat will often end with it dashing off somewhere. Try to understand how far they can dash, then have a bomb ready, once they dash towards you drop the bomb and run (or shield if they are going to bite), the kat will often stop on the bomb if you drop it in the right spot.

Blast bombs are interesting, if you can judge where the bomb is going to knock an enemy then you can guess where to place your next bomb.

The Fiery haze bomb is good for running around and dropping as many bombs as possible, eventually everything melts to death.

As for Sprites they work good

Drakon can work as a free ranged attack with fire, improved defense and fire spread, or a second fire bomb
Seraphynx makes for a good hit and run with its beam, more HP for you, or a shield that lets you charge while protected
Maskeraith can stop healing and works with damage over time statuses, you can cloak and get out of trouble, or deal even more group damage

For all of these you need to feed them as much as possible because eventually you will get a bomb CTR perk and any CTR perk for a bomber is good.

@ Vohtarak

I know there is a guide but it gives advice on endgame bombs and equipment not, unlike the other classes being a newby bomber is significantly harder and there is no guide to help them out.