I've been reading this forum for a very long time, since I started playing FFXIV about one month following launch, but just now decided to make my very first post ever :). I've noticed how difficult some people think it is to solo, so I wanted to make a very simple list with how I personally am getting absolutely fine EXP solo. A lot of these things may seem obvious to some, but here we go!
1. Use gear your level or below.
I have been using gear lower than my level, anywhere from 3 to 10 levels lower. At first, I too was using my old level 50 gear, and having a difficult time like many people are. However, I got new gear and, low and behold, my DEF doubled. (Even with gear up to ten levels lower!) I went from being able to barely solo a monster the same level as me, to being able to take on monsters up to four levels higher fairly easily.
2. Fight things within your five level range.
For example, I was level 28 and was fighting level 25-29 monsters, and when I got 30, I switched to monsters level 30-34. This allowed me to chain relatively easily. If you notice, monsters usually range in five level ranges like that everywhere in Eorzea. 25-29, 30-34, etc. With gear your level, as stated above, you should be able to easily kill two mobs (even at the same time!) and chain them. But I took advantage of the speedy kills of enemies slightly lower than me as well. If you balance out the kills, Second Wind will keep you alive on its own.
3. Equip any and all "reactionary" skills that you can.
This means WS that you can use after Evading, Blocking, Parrying, etc. When fighting things your level or near your level, monsters will miss you... a LOT! I can easily spam Jarring Strike and Fracture up to 8 times a fight. I'm sure that GLAs with Phalanx can do even better! Best part? They are only 250TP! Spam away! Honestly, I feel your character parries, blocks, and evades more after the patch, but it may just be because I'm no longer fighting things 12 levels higher than me. Also, take note that Evading has been done away with, so skills based on "Evading" attacks now work with any monster MISS. This is huge for Jarring Strike! For those that don't know, Jarring Strike also stuns enemies :)
4. Other Helpful skills:
Defender, Sentinel, Cure II or Sacrifice II (or 3!), Feint, Skull Sunder II (you can see noticeable DoT on enemies your level), Arrow Helix (any AoE, for when finishing one mob an going to another. Why not do some damage to start the next fight while finishing the current one? :D), and Featherfoot (Now restores MP too!).
I was able to pull in anywhere from 20k-30kEXP an hour in Mun-Tuy Cellars using these strategies, with absolutely no sweat. Hopefully, people can post their own helpful advice as well, maybe something I didn't think of? Of course, these things all require that you have the skills, or gil to buy equipment, but I see people complaining about all level ranges so just wanted to share this.