Updated: Nov 7, 2022
In the base game of Catan, the recipe of a road is the cheapest and the easiest to remember - 01 Brick + 01 Wood. Among purchasable options, a road is the only unit that does not individually provide any Victory Points. When considering on a larger scale, the Longest Road holds the potentially highest resource-to-point ratio: 26 resource cards (13 roads) for only 02 VPs. So far I have been making roads look like the symbol of ineffectiveness, but that is not what this thread is about. For the remaining parts, we will be covering as many aspects relating to road strategies as possible.
First turn road is a thing - that statement is applied to every party in the Game. The possibility of someone (could be either you or your opponent) cutting another off right in their first turn exists and oftentimes it is worth being done. The second starting settlement yields resources around it, and it is everyone's favourite to start with something useful like a road or a development card. Therefore, if you cannot use them to your advantage, watch out for bad intentions.
Avoid placing roads insecurely. When an opponent is near the spot you are aiming toward, it is unwise to go there step by step. You always have to be aware of opponents' hand cards, as well as face-down dev. cards. Building a flexible road is fine, but do not put ones that would become completely useless if got blocked (either by roads or a settlement). Instead, you should hold on to your cards until you can afford to put both your road(s) and settlement down.
03 straight roads - 01 settlement - despite being not applicable in every game, is an effective tactic when pulled off successfully. There are boards where other people will be heading for ports, meaning plenty of space in the centre will be available for you to expand. By building 03 straight roads before putting down a settlement, you ensure no 02 settlements of yours are adjacent to 01 hex. Doing so will both dissuade the robber and reduce your dependence on luck.
Planning toward your future Longest Road is necessary and should be thought through before placing your second starting settlement. Although the shapes of roads seem to vary infinitely, there are worth-remembering details about certain regular formations. While you need 06 roads to form a single-hex loop; a double-hex loop (no road inside) only needs 10 roads. Apparently, there exist 02 variants with triple-hex loops, a 14-road bar shape, and a 12-road triangular one. And last but not least, a diamond-shaped quad-hex loop requires 14 roads. A dedicated road builder ought to foresee every route available to lengthen their road, even extend it to a maximum of 15 if needed.
Remember to trade for an upgrade early when there is no Ore hex available within your reach. Do not wait until you get stuck at 07 VPs with the Longest Road and 05 settlements. Once the opponents realise the situation you are in, they will either ignore your request for Ore or offer you a price far more expensive than you expected. Assuming you already have a sufficient amount of Wheat, "02 roads for 03 Ore" is usually the standard deal to offer people.
In case you find anything related to building roads not mentioned, please remind me in the comment section. Also, I would appreciate it if you could drop a like and share my blog around. Thank you so much for reading and see you again!