Here are my mods and two cents worth of information

[I'm goin' down]

I started this game from scratch. I latched on the Rockin Robbins, watched almost every tutorial produced (many which I did not understand for several months), and then made a breakthrough with Hitman's classic tutorial on Manual Targeting at 100 percent realism, which teaches the theory behind manual targeting. I have gotten fairly proficient at attacking and sinking ships. I also have experiented with almost every mod out there. I have settled on these. Where they really help, I make note.

Here is my current list of mods:

1. Trigger Maru_Overhaul 1.7-I used to play TMO/RSRDC combined, but recently discovered TMO standing alone is an excellent piece of work. I gave up on RFB because it does not display the torpedoe angle on the Attack Map with any degree of percision, which is indispesible if you use the Easy AoB mod. See discussiion, infra. FOTRS is a very good game mod also. Great colors, but not as tough as TMO. FOTRS has planes coming out of the wood work.
2. TMO Hotfix_041709--
3. Optics2 over TM (by Werner Sobe). I chose this over "Max Optics &SCAF fix TMO1.7_41109", although the TMO thread reommends Max Optics. This mod is used to find range and aspect ratio on the TGT dial for application in manual targeting.
4. (1)RUIMv1.0 for SH1.5; (2)RUIMv1.0 forSH1.5 Enlisted Ranks add-on; (3) RUIMv1.0 for SH1.5; RUIMv1.0 for SH1.5 Award Add-on. An eye candy mod package.
5. EZ_Plot_V1.0; I have not tried TMOPlot_Final. These mods are supposed to change the sillouttes of the targets but I have not seen any changes yet.
6. RCM_Imperial. Adds color to the radar screen and supplies range to the ships appearing on the radar screen.
7. TMO_Deckguns_M32_paint (making harder for the enemy to recognize.) This is an optional mod in the TMO download.
8. TMO_Stern_DeckGuns. This is an optional mod in the TMO download.
9. Webster's Real Lifeboats Fix for 1.5. It works with TMO.
10. Webster's Smaller Rain for TMO. (It hasn't rained yet!)
11. Webster's Reduced Radio Fix Traffic for v1.4 & 1.5. It works with TMO.
12. Note: I did not mod in Webster's Better Air Patrols, but incorporated the suggested cfg file changes from his mod into the corresponding data files in both TMO1.7 and SH4v.1.5, just to cover my rear end. I had concerns that incoporating the mod via JGSME would not fix the air patrol issue in the TMO airstrke file. I have far fewer air patrols to contend with.
13. Note: I did not mod in Webster's faster TC Near Land for v1.5, but incorporated the singe file change from his mod as set forth in the Readme for the mod. This improves boat speed near land.
14. TGT Dials to PK Fix -1.5. This the Easy AoB mod. It works even though it is not designated for TMO. The designated download is "TGT Dials to PK Fix - TMO," which I could not get to work. This mod is a game changer in attack theory, and you can see its effectiveness in real time game play by viewing the Attack Map for precision firing. It is also used in conjuntion with Optics2overTM mod (see item 3, above.) to get a target's correct range/aspect ratio. For the basics on the necessiity of determining the correct aspect ratio in a successful attack using manual targeting, see Hitman's classic tutorial on Manual Targeting at 100 Percent Realism (it is a pdf download). The Easy AoB mod is the heart of my attack strategy against 1, 2 or 3 ships. I haven't hit four target's yet, but I am trying. I do not see four target's that often.
15. Fred's radio files.
16. SH4_Ultimate_Soundmod Fix
17. When you are totally committed, read Aaronblood's tutorial on MoBo, download and use it. It is not a mod, but it a hell of a piece of work.
18. SD3-not a mod. Peabody showed me how to use it to shorten the reload time on my deck gun. I have the reload time down to a couple of seconds now. This modders tool is too advanced for me to work with.
19. Custom boat - SS 111, USS Barbarrina, a Gato, designed by Kill Flags mod team, with the emblem compliments of Gunfighter.

For beginners, I would take on the game in the following order:

1. Auto targeting. Get it down cold, learn to operate your boat, read the map, use the map tools, and start reading posts on topics that interest you or will help your performance. The key forums are the SH4:Wolves of the Pacific (i.e. this fourm) and SH4 Fleetboat Mods Workshop forums. Become familiar with them, and learn to use the search feature to look for threads/posts which may address an issue you have. There is literally a library of information in the forums. MoBo, mentioned above, is in a separate forum.
2. Watch and read every Noob tutorial you can get your hand on.
3. Manual targeting-Start the Dick O'Kane method; Hitman's tutorial on Manual Targeting at 100 Percent Realism; Werner Sobe's and Rockin Robbins video tutorials on manual targeting, followed by their sonar only videos; John Cromwell attack method; End up with the Easy AoB mod.
4. Don't be discouraged if your boat is sunk/killed a lot. Once you are lucky enough to escape detroyers' depth charges, you could very well be bombed into submission by an airplane or several of them. The Japanese came to play baseball, not eat sushi!
5. When you feel you are ready, order a custom boat and emblem for the Kill Flags team (mod forum).
6. Be wary if someone claims to sink 40K tonnage per mission at realistic levels. They are probably not playing at full realism, or, instead of docking, are refueling to continue the mission to rack up kills. It's not like anyone is checking.
7. Have fun.