I am 35 years old and have made personal finance a goal this past year.

I'm not particularly sophisticated when it comes to money and have made some gross errors in the past which has also made me very cautious about my decision-making. I'm glad I've come a long way in shedding debt, but I need advice in how to acquire better financial skills to the next level.

I've paid off my substantial credit card debt and haven't carried a balance for several years now. I had paid cash for my car, a 10 year old beater than I plan on driving until it's no longer worth it to repair (driving an ugly car doesn't bother me).

I don't have a high wage and because I started saving late (at age 28), I currently contribute ~18% of my income to my 401k.

I know that people on this forum have advised to contribute up to the 401k match, then IRA, then the rest back in the 401k. What's the idea behind this? What's the best way to pick funds and diversify? How do I know if I'm on track for retirement?

I also participate in my employer's ESPP (10%). So far, I've just been cashing out right after the shares are released but I've just learned about disqualifying dispositions and I'm guessing that it would be probably advantageous to hang onto those shares, right?

Charitable, religious and contributions are also one of my priorities (10% of my pretax). There's really not a lot of money left over and while I'm able to live within my means and still save, I'd like to have a better plan so I can feel more comfortable with discretionary spending. How much I should keep in an EF and how much I should save for my other goals (car fund, house fund, going back to school)?

Welcome!
People recommend putting up to the match in your 401k because it's pretax. When you retire (or get older-whatever), you want to have some money pretax, and some money post-tax (Roth), so that your tax liability isn't so large when you stop making money. Putting in the match gets you your free money from your company, and then you put the rest in a post-tax account. If you still have leftover money, put the rest in pre-tax and call it a day. But, that's neither here nor there if you don't have a liquid (fairly easily accessible) emergency fund.

So, get an emergency fund together if you don't have one. The amount you keep depends on your situation. Most people say job loss, furnace goes out, roof gets a huge hole in it, car dies etc... Calculate how much you think you need and start funneling away. You can't take out of your retirement, so make sure you have money in the bank for your emergencies. I'm still building my Efund while I contribute to my Roth and my 401k. Luckily, I'm almost done.

There are online retirement calculators, so use that to see whether you have enough for your age, etc..they all give different numbers, so use a couple and see what it says.

As far as choosing what funds to invest in, there are tons of books (search the forums for book recommendation or website recommendations), and it will help you figure out what your risk tolerance is, and where you should put your money based on that. That is also an individual decision.

I don't know anything about getting shares of a company so I can't help you there. Any other questions, just ask. I would check out these forums and search for stuff. There is a TON of information and it's easier to do your own research and then ask if you're confused about something.

Thanks for explaining. I plan on contributing less to my 401k in order to fully fund my Roth IRA by the end of the year. My employers also offer the Roth 401k; should I be doing that instead of traditional 401k? A split?

I have some cash and some mutual funds and ETFs that I plan to use to fund my EF. As a rule of thumb, how to figure out how much I need an EF? Should it be based on my expenses? My salary?

The rule of thumb for an EF is 3-6 months worth of expenses. Are you single with a stable job? Maybe you just need 3 months. Is your job in jeopardy because of the economy? I'd go to 6 months. Do you have dependents? Little bit more. It boils down to being whatever will give you peace of mind.

I don't know anything about a Roth 401k.