First off - the best reason to go into S & I - is because you think it's fun. If you don't think it's fun ... don't do it. Try it on a small scale and see how you like it. If you do - do some more. If you don't - go do something else.
That said ...
1) Your Rifter
has only two minerals you can't mine (for the most part) in Hi Sec, Zydrine and Megacyte. Nocxium comes from Pyroxeres
which is readily available in certain areas (such as Caldari) space. One source of the minerals you don't have (besides just buying them) - is to melt down items that you have bought or looted.
2) If you want to get involved in Industry - first learn Trading. Nothing you make is worth anything to you (except for your own use) if you don't sell it. So - Trading - is the place to start. Learn the market first, how to use it, how it works, what costs what, where - and you'll have a better idea of what to make and where to sell it. That and hopefully you'll learn how to make money just off the market itself. Then - if you go into Industry - you'll know where to get (or how to find out where to get) the things you need.
3) As importantly - you'll learn how to judge which method of several available that you want to use on a specific occasion to acquire what you need. Market prices and availability vary. Scale matters - what is a good way of getting things for small scale production (like your own loot) isn't sufficient for large scale manufacturing.
4) Know the value of things, not merely their market value but their value to you. If mining and trading are boring - then no matter how much more money you might make through spending more of your time learning about them - then they aren't worth it in a game you are (supposed to be) playing just for the fun of it. Be aware of the cost to you of the time you spend doing one thing as opposed to another - both financially and fun wise. Understand the market value of the minerals you use to make something - are you better off just selling them than making what you were going to make? Yes - you can make more money than you had - but are you making as much money as you could? Is what you would have to do to make as much money as you could - worth it to you in costs of fun? It doesn't matter what something is selling for in Jita - if Jita isn't a practical option for YOU.
5) Asteroids, Loot and Salvage - are free for the taking - as long as the local corporation isn't charging you for them. But that doesn't mean that there isn't a cost associated with acquiring them - in addition to whatever the local corporation may or may not be charging you for them (which doesn't, to my knowledge, happen often). There are many costs, some one time, others recurring and the more ambitious your plans the greater these costs will be. Do personal research on just what it is that you are going to have to do to accomplish something - before you do it. The more Anal Retentive you are about this (spread sheets are your friend), the more money you can save/make at it. Most things in EVE have a steep learning curve. You can start out really easy. The threshold for getting into manufacturing is trivial. However - the costs rise steeply as you become more ambitious.
6) The production process is:
Mine -> Refine -> Manufacture -> Transport -> Trade*
*(Trading is the only one not optional).
At each step along the way - there are efficiencies to be gained. The more of these steps you take - the more efficient your operation will be. Many of these efficiencies are effected by your Standings with the NPC corporation owning the station you are using. These Standings can only be increased by running missions.
7) Location. The Station, System, Region, Faction Space you use all makes some difference - to you - based on what YOU want to do and what Agents, Ores, Markets you want to use.