For wire, I use copper clad steel from Wireman

"Fabricated 14 AWG solid copper clad steel (30%). The best choice for long-lived, high performance antennas in any environment. Breaking strength 550 lbs. fabricated and coiled on large diameter reels to retain a 'memory' of close to straight for easy assembly, it does have a bit of a 'mind of its own', making it somewhat tough to work with, but well worth the effort as the best propagator and longest lived."
http://thewireman.com/antennap.html

My dipole, 270 feet in total length, has been up for 10 years (one leg came down during Sandy, pulled out of the insulator - did not break, now back up in the air).
Highly recommended.

The other is ladder line length.

From my notes on ladder line lengths:
From MFJ tuner manual....
1. Never center feed a half-wave multi-band antenna with a high impedance feedline that
is close to an odd multiple of a quarter-wave long.

2. Never center feed a full-wave antenna with any feedline close to a multiple of a halfwave
long.

3. If a tuner will not tune a multi-band antenna, add or subtract 1/8 wave of feedline (for
the band that won't tune) and try again.

4. Never try to load a G5RV or center fed dipole on a band below the half-wave design
frequency. If you want to operate an 80 meter antenna on 160 meters, feed either or
both conductors as a longwire against the station ground.

To avoid problems matching or feeding any dipole antenna with high impedance lines,
keep the lines around these lengths. The worst possible line lengths are shown in
brackets:
160 meter dipole; 35-60, 170-195 or 210-235 feet. (Avoid 130, 260 ft)
80 meter dipole; 34-40, 90-102 or 160-172 feet. (Avoid 66, 135, 190 ft)
40 meter dipole; 42-52, 73-83, 112-123 or 145-155 feet. (Avoid 32, 64, 96, 128 ft)