Everyone I know who is interested in model railways and railroading are very passionate people who spend hours on hours perfecting there model. It's important that you realize that there is always someone who is better than you model railroading who can help and advise you on how you can develop your railway further.
Forums are very popular; modelers in particular all have a desire to share everything that they have learned about models and creating the perfect model railroad with other people who are interested in the same hobby as they are. You can learn a lot from these people especially if you are still quite new to making model trains and railways. Some of the people on these forums have been interested in model trains for 30, 40 years, maybe more than that so certainly have a lot of information to share.
You can get feedback from likeminded people on your model; you can post pictures of your railway and get feedback on it. Or maybe you are working on improving a part of your model railway you can ask advice on forums and people can help you improve it. Maybe if you know a little about model trains you can help other people and give them advice, forums like this welcome beginners as well as experts.
On some model railway forums you will be able to buy second hand model trains from other members; this could save you a lot of money buying new model trains. Often meet ups are arranged on these forums. On some of the larger model train forums you will also find people who have written books about model trains, manufactures of the trains as well as enthusiasts who own a store selling specialist model trains.
You can talk with members on these model railway forums about anything from buying a model train to creating scenery. It's always a good idea to get help and advice from people who have more experience than you; other members will also be really pleased to get help and advice from you as well.