Wondering about painting my house, best paint..tips tricks?

We recently purchased our first home, we went over budget fixing up the inside and doing some remodeling...now were wondering what we can do for the outside. We have an older siding, its aluminum looking...thicker meaning wider panels. Its white currently, and I'd like to keep it that way but its very dingy looking. We were told it could be painted but neither my husband or I have a clue what steps we need to take to paint it. I read online that Sherwin Williams is the best paint for exterior painting but I was wondering if anyone had any tips or tricks...paint suggestions? What type of brush do you use or tools? Any help would be very beneficial. Thank you!