Warfare & Tactics

If you want to make isk and also learn to pvp I'd say join faction warfare.

You can get the best of both worlds then.

Several corps have logistics setup to import ships in for fellow corp members.

Your plan to join a merc corp at such a young age is an ambitious one. Having been in a few notable HS merc corps over the past couple years myself, let me give you a few tips.

1. Locator agents. Not sure if you know about these yet, but you will need locator agents to be an effective merc. It's a sad irony that any effective HS wardeccer needs to carebear it up for a month or two in order to gain access to lvl 3 and 4 locator agent standings with at least one of the four empires, but make no mistake; joining a merc corp without access to these will result in one of two outcomes: Either you'll constantly be pestering your corp mates to run locates for you (This gets very annoying,) or you'll eventually end up leaving corp to obtain said standings, and might not be allowed back in. (Alternatively you can pay 5 mil per locate in the locates are us channel, but who the hell wants to do that.)

2. Neutral alt. Mercs live and die by their neutral alts. Sub an alt, give it a name not similar to your main's, keep it out of your corp and any player corp (It's called neutral for a reason,) and train it into a cov ops cloaky/scanning frigate like a Helios at the very least. Natural progression along this path will lead you into a link ship and other things, but the cov ops frig is the most important. It takes about a month to train the requisite skills for one. Get started now while you're learning to PVP.

3. Jump Clones. I personally don't run with JC's but many many mercs do, especially those with implants and slaves, snakes or halos. Consider hitting up EACS (Estel Arador Corp Services) before you apply to your merc corp so that you can create as many JC's as you have skill to for free.

4. It's gonna take you longer than 3 months to learn how to PVP. HS mercing isn't the hardest thing in the world to do but it does take a bit of skill, good timing, knowledge of aggression mechanics, enemy ship capabilities and other stuff. Consider that you might be with your initial training corp for a while longer than 3 months.

5. Your most effective ships for day-to-day merccing are small, fast, high-dps ships. Align fast, move fast, lock fast and warp fast, you'll be the bane of many a ships existence. Sure, there are occasions when you want something heavier, but for 90% of the HS targets out there, a combat interceptor is ideal. Do yourself a favor and check out the Taranis.

Most important thing to understand here is that whatever you fly, you need locators, and a good, neutral, non-suspicious alt.

Edit: Also note that you may have difficulty even finding a merc corp to join simply due to your age. Many merc corps don't take people with less than 10 or 20 mil SP unless you already have a great KB. Considering you're gonna be coming from a PVP training corp, that won't be the case. There are, however, a few corps out there that offer training programs.

Confirming this is a rather important point,
speaking from experience it's a pain in the arse when after the first week of a war all the war targets know your scout and get sketchy when they see it (because you're obviously one or two jumps away).

Mine was from before I started in the merc business and iv been kicking myself about it ever since (though the t2 links kinda make up for it).

Though the rest of Justin's post is quite accurate I felt it worth stressing this point in particular.