I would suggest starting in T2.

T1 Lockdown's really the only odd one out -- T2 and T3 lockdown fuction effectively the same, except with different gears that add subtle differences to the dynamics. In T2, your heavy swords are limited to pure normal, while in T3, you gain part elemental/part shadow, and the defenses change as such. Also in T2, you are limited to Dusker while T3 allows you to run any wolver armor, and that changes your abilities accordingly.

I highly disagree that "tactics and techniques" matter less. The only difference is that the T2 playerbase is, on a whole, less skilled than the T3 playerbase, as only a few endgamers really venture down there to play. It should be noted that your gear makes a HUGE difference, and your gear choice does so as well; not just in how you play, but how much you can take, from which weapons, and what to look out for. This is a concept inherent to the game's design, so it should hardly come as a surprise.

One other plus of starting in T2 is that the general players use NO UVs, as opposed to the incredible UV-toting players that swarm T3 LD. I'm not gonna say there are NO UV users, but there are quite a lot less of them -- your average ASI of a striker drops to high, as opposed to the pretty much Max-Ultra pace of T3; that makes it not only more beginner friendly, but less expensive.

I would start T2 LD with this:

Dusker set
2x Tri-hearts
Swift Flourish (if you can afford an ASI low flourish, which goes for about 5k cr, and then upgrade it from there, all the better)
Antigua, Kilowatt Pulsar, Sealed Sword/Grintovec/Rocket Hammer, nightblade (if you have it)

Although 6 weapons are listed (SS/Grinto are the same thing), I would suggest starting with two slots and just alternating your weapon switches there; smooth weapon switching is a key to success. Bombers and Gunners as a whole are a lot less deadly in T2, so your main concern should be taking out people geared just like you: dusker + flourish.

Your primary shoudl pretty much always be flourish, and your secondary should be whatever helps you out. I typically switch between Antigua (for 1v1) and Kilo (for crowd control), though I'm starting to incorporate Nightblade as a defensive option/KO option.

Otherwise, a lot of LD is learned by playing. Here are a few random tips I can think of on the top of my head and might give you a jumpstart in LD, but otherwise, good luck.