I struggle with alignment, a lot. Getting parts to fit and adhere correctly is crucial in building a model (especially if you seek the great fame, wealth, and glory that accompanies a win at an IPMS contest), so lately I've been masking areas that will serve as mating surfaces for two parts. For example, on the B-26 I just finished I used thin strips of Tamiya tape to mask the narrow areas where the bulkheads joined the fuselage. This, I hope, provides a strong bond of those parts.
To DutyCat's observation on ARC, I've been using Micro Mask to ensure that the holes and mating surfaces for landing gear and wheels remain clean of paint, which eases assembly and ultimately provides a strong bond. Is all of this tedious? Yes, but anything that helps me during assembly is a good thing.
I love weathering. It's my favorite part of the model building process, and for me it begins with painting and ends with paint chips. I used to use silver paint to represent paint chips, but I've found that it's not condusive to creating "chips" small enough and jagged enough to look realistic. I've seen well-painted models with paint chips that resemble silver amoeba rather than irregular and jagged damage.
A better medium for me has been artist pencils. Using an inexpensive pencil sharpner, I can get them sharp enough to create very fine "chips," lightly tapping the pencil on the model to create the smallest chips. The trick then becomes creating chips that appear realistic, which is difficult and time consuming. I spent approximately two hours on the paint chips on my B-26.
I'm a proponent of scale effect. I won't bore you with a technical explanation, but if you're new to the hobby the concept simply suggests that colors become less intense in smaller scales. For me it means that I never use paint directly out of the bottle. Every color I apply to a model is muted or altered in some way, and it's especially true of the so-called primary colors (red, orange, yellow, green, blue, indigo, violet), and white and black. I always reduce the intensity of these colors by adding another color to them.
For example, my B-26 features black and white D-Day invasion stripes. Rather than apply those colors directly from the bottle, I added a little tan to the white paint and white and tan to the black paint to weather them and avoid the stark contrast that a bright white and dark black would impart. The same holds true for the yellow on the tips of the propeller blades, which was toned down using tan and white.
I hope you can use these ideas for your models. I'll share some additional tips in the future.