For altitude events using optical tracking, it is highly recommended to use tracking powder in your model. This produces a small “cloud” at ejection which the tracking crew looks for. Without tracking powder, it is not likely your model will get tracked.
Dry Tempera paint or a fine powdered Fluorescent Dye are often used for tracking powder. Some contestants used to rely on powdered chalk (from home supply/hardware stores like Home Depot or Lowes). However, it is clumpy and does not produce much of a tracking cloud for the volume/weight of the powder. Red is a good color choice for tracking powder, though some like to use black if there is a high overcast or hazy “white” sky. Fellow competitors are often willing to share tracking powder.
Here’s a good way to install tracking powder. After installing wadding, pack the parachute and shock cord into the model, and push them down into the tube to leave room for the tracking powder in the upper part of the tube. Use a piece of wadding or plain paper to make up a long narrow “cup” than will easily slide inside the body tube. Press that cup into the tube, then pour in the tracking powder to fill the cup. About 1″ or so depth of powder is a good ballpark. Using tracking powder can require greater forces to expel everything out of the body, which sometimes results in the engine kicking out instead (however, the cup method reduces this problem a bit compared to just dumping powder into the tube). Make sure the engine is secured in the rocket extra-tight. Some people like to attach the fins a bit above the bottom of the body tube so they can apply a “collar” wrap of tape to the bottom of the tube and the engine. This helps prevent the engine from ejecting.