Use your 401K .
Avoid direct investing in HOT stocks. Stick to a diversified portfolio.
Be positive at work, be the guy willing to jump in and lend a hand. Don't be the guy that says "not my job description" - he goes nowhere. This pays dividends in raises, promotions and stock options-all which will move you along your path to FIRE quicker.
In engineering, you will be placed in many situations where your product path is determined by scientific basis or best estimates as the full answer is not yet available. Its amazing how many theories come out to support one direction or another-all seemingly valid heh.
Be careful not to fall into the trap of entrenching yourself on a side because of your own contribution to it. Realize that Not-Invented-Here syndrome is an impediment to solid scientific judgement and product development. It is your EGO talking, not the science.
The engineering world of chock full of ego's...don't be them. They will be clawing over your back to get ahead. Don't be them. They will be fretting everytime someone other than themselves makes a contribution. Don't be them.
Do not assume good work and solid contributions alone will promote you. You need to be willing to do some self promotion- this is a tricky balance you'll have to find for yourself.
Pay attention to stuff outside your realm...marketing, business, finance guys all have a view of the company you don't get from your desk. Have friends in various places in the organization, keep conversations going with them.
Don't forget that science is fun.
Don't forget that science is hard and explaining science is even harder. Learn how to assess the level of your target audience on the fly and modify your words to that level of understanding. Dumping a bunch of science jargon on C-levels does not tilt them in your favor.
Don't forget that science is fun.
Good luck !